diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 2e508d4..c7f6fc7 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -15,6 +15,10 @@ jobs:
           node-version: '20'
           registry-url: https://registry.npmjs.org/
       - run: npm ci
+      - run: npm run build
+      - name: Check that KaitaiStream.js will be included
+        run: |
+          npm publish --tag next --dry-run --json | jq --exit-status '.files | map(.path) | any(. == "KaitaiStream.js")'
       - name: Publish to npm
         run: npm publish --tag next
         env:
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..86df457
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,5 @@
+/node_modules/
+
+# Generated by Typescript compiler
+/KaitaiStream.d.ts
+/KaitaiStream.js
diff --git a/KaitaiStream.js b/KaitaiStream.js
deleted file mode 100644
index 473b065..0000000
--- a/KaitaiStream.js
+++ /dev/null
@@ -1,948 +0,0 @@
-// -*- mode: js; js-indent-level: 2; -*-
-'use strict';
-(function (root, factory) {
-  if (typeof define === 'function' && define.amd) {
-    define([], factory);
-  } else if (typeof module === 'object' && module.exports) {
-    module.exports = factory();
-  } else {
-    root.KaitaiStream = factory();
-  }
-}(typeof self !== 'undefined' ? self : this, function () {
-
-/**
-  KaitaiStream is an implementation of Kaitai Struct API for JavaScript.
-  Based on DataStream - https://github.com/kig/DataStream.js
-
-  @param {ArrayBuffer} arrayBuffer ArrayBuffer to read from.
-  @param {?Number} byteOffset Offset from arrayBuffer beginning for the KaitaiStream.
-  */
-var KaitaiStream = function(arrayBuffer, byteOffset) {
-  this._byteOffset = byteOffset || 0;
-  if (arrayBuffer instanceof ArrayBuffer) {
-    this.buffer = arrayBuffer;
-  } else if (typeof arrayBuffer == "object") {
-    this.dataView = arrayBuffer;
-    if (byteOffset) {
-      this._byteOffset += byteOffset;
-    }
-  } else {
-    this.buffer = new ArrayBuffer(arrayBuffer || 1);
-  }
-  this.pos = 0;
-  this.alignToByte();
-};
-
-
-KaitaiStream.prototype = {};
-
-/**
-  Dependency configuration data. Holds urls for (optional) dynamic loading
-  of code dependencies from a remote server. For use by (static) processing functions.
-
-  Caller should the supported keys to the asset urls as needed.
-  NOTE: `depUrls` is a static property of KaitaiStream (the factory),like the various
-        processing functions. It is NOT part of the prototype of instances.
-  @type {Object}
-  */
-KaitaiStream.depUrls = {
-  // processZlib uses this and expected a link to a copy of pako.
-  // specifically the pako_inflate.min.js script at:
-  // https://raw.githubusercontent.com/nodeca/pako/master/dist/pako_inflate.min.js
-  zlib: undefined
-};
-
-/**
-  Virtual byte length of the KaitaiStream backing buffer.
-  Updated to be max of original buffer size and last written size.
-  If dynamicSize is false is set to buffer size.
-  @type {number}
-  */
-KaitaiStream.prototype._byteLength = 0;
-
-/**
-  Set/get the backing ArrayBuffer of the KaitaiStream object.
-  The setter updates the DataView to point to the new buffer.
-  @type {Object}
-  */
-Object.defineProperty(KaitaiStream.prototype, 'buffer',
-  { get: function() {
-      this._trimAlloc();
-      return this._buffer;
-    },
-    set: function(v) {
-      this._buffer = v;
-      this._dataView = new DataView(this._buffer, this._byteOffset);
-      this._byteLength = this._buffer.byteLength;
-    } });
-
-/**
-  Set/get the byteOffset of the KaitaiStream object.
-  The setter updates the DataView to point to the new byteOffset.
-  @type {number}
-  */
-Object.defineProperty(KaitaiStream.prototype, 'byteOffset',
-  { get: function() {
-      return this._byteOffset;
-    },
-    set: function(v) {
-      this._byteOffset = v;
-      this._dataView = new DataView(this._buffer, this._byteOffset);
-      this._byteLength = this._buffer.byteLength;
-    } });
-
-/**
-  Set/get the backing DataView of the KaitaiStream object.
-  The setter updates the buffer and byteOffset to point to the DataView values.
-  @type {Object}
-  */
-Object.defineProperty(KaitaiStream.prototype, 'dataView',
-  { get: function() {
-      return this._dataView;
-    },
-    set: function(v) {
-      this._byteOffset = v.byteOffset;
-      this._buffer = v.buffer;
-      this._dataView = new DataView(this._buffer, this._byteOffset);
-      this._byteLength = this._byteOffset + v.byteLength;
-    } });
-
-/**
-  Internal function to trim the KaitaiStream buffer when required.
-  Used for stripping out the extra bytes from the backing buffer when
-  the virtual byteLength is smaller than the buffer byteLength (happens after
-  growing the buffer with writes and not filling the extra space completely).
-
-  @return {null}
-  */
-KaitaiStream.prototype._trimAlloc = function() {
-  if (this._byteLength === this._buffer.byteLength) {
-    return;
-  }
-  var buf = new ArrayBuffer(this._byteLength);
-  var dst = new Uint8Array(buf);
-  var src = new Uint8Array(this._buffer, 0, dst.length);
-  dst.set(src);
-  this.buffer = buf;
-};
-
-// ========================================================================
-// Stream positioning
-// ========================================================================
-
-/**
-  Returns true if the KaitaiStream seek pointer is at the end of buffer and
-  there's no more data to read.
-
-  @return {boolean} True if the seek pointer is at the end of the buffer.
-  */
-KaitaiStream.prototype.isEof = function() {
-  return this.pos >= this.size && this.bitsLeft === 0;
-};
-
-/**
-  Sets the KaitaiStream read/write position to given position.
-  Clamps between 0 and KaitaiStream length.
-
-  @param {number} pos Position to seek to.
-  @return {null}
-  */
-KaitaiStream.prototype.seek = function(pos) {
-  var npos = Math.max(0, Math.min(this.size, pos));
-  this.pos = (isNaN(npos) || !isFinite(npos)) ? 0 : npos;
-};
-
-/**
-  Returns the byte length of the KaitaiStream object.
-  @type {number}
-  */
-Object.defineProperty(KaitaiStream.prototype, 'size',
-  { get: function() {
-    return this._byteLength - this._byteOffset;
-  }});
-
-// ========================================================================
-// Integer numbers
-// ========================================================================
-
-// ------------------------------------------------------------------------
-// Signed
-// ------------------------------------------------------------------------
-
-/**
-  Reads an 8-bit signed int from the stream.
-  @return {number} The read number.
- */
-KaitaiStream.prototype.readS1 = function() {
-  this.ensureBytesLeft(1);
-  var v = this._dataView.getInt8(this.pos);
-  this.pos += 1;
-  return v;
-};
-
-// ........................................................................
-// Big-endian
-// ........................................................................
-
-/**
-  Reads a 16-bit big-endian signed int from the stream.
-  @return {number} The read number.
- */
-KaitaiStream.prototype.readS2be = function() {
-  this.ensureBytesLeft(2);
-  var v = this._dataView.getInt16(this.pos);
-  this.pos += 2;
-  return v;
-};
-
-/**
-  Reads a 32-bit big-endian signed int from the stream.
-  @return {number} The read number.
- */
-KaitaiStream.prototype.readS4be = function() {
-  this.ensureBytesLeft(4);
-  var v = this._dataView.getInt32(this.pos);
-  this.pos += 4;
-  return v;
-};
-
-/**
-  Reads a 64-bit big-endian unsigned int from the stream. Note that
-  JavaScript does not support 64-bit integers natively, so it will
-  automatically upgrade internal representation to use IEEE 754
-  double precision float.
-  @return {number} The read number.
- */
-KaitaiStream.prototype.readS8be = function() {
-  this.ensureBytesLeft(8);
-  var v1 = this.readU4be();
-  var v2 = this.readU4be();
-
-  if ((v1 & 0x80000000) !== 0) {
-    // negative number
-    return -(0x100000000 * (v1 ^ 0xffffffff) + (v2 ^ 0xffffffff)) - 1;
-  } else {
-    return 0x100000000 * v1 + v2;
-  }
-};
-
-// ........................................................................
-// Little-endian
-// ........................................................................
-
-/**
-  Reads a 16-bit little-endian signed int from the stream.
-  @return {number} The read number.
- */
-KaitaiStream.prototype.readS2le = function() {
-  this.ensureBytesLeft(2);
-  var v = this._dataView.getInt16(this.pos, true);
-  this.pos += 2;
-  return v;
-};
-
-/**
-  Reads a 32-bit little-endian signed int from the stream.
-  @return {number} The read number.
- */
-KaitaiStream.prototype.readS4le = function() {
-  this.ensureBytesLeft(4);
-  var v = this._dataView.getInt32(this.pos, true);
-  this.pos += 4;
-  return v;
-};
-
-/**
-  Reads a 64-bit little-endian unsigned int from the stream. Note that
-  JavaScript does not support 64-bit integers natively, so it will
-  automatically upgrade internal representation to use IEEE 754
-  double precision float.
-  @return {number} The read number.
- */
-KaitaiStream.prototype.readS8le = function() {
-  this.ensureBytesLeft(8);
-  var v1 = this.readU4le();
-  var v2 = this.readU4le();
-
-  if ((v2 & 0x80000000) !== 0) {
-    // negative number
-    return -(0x100000000 * (v2 ^ 0xffffffff) + (v1 ^ 0xffffffff)) - 1;
-  } else {
-    return 0x100000000 * v2 + v1;
-  }
-};
-
-// ------------------------------------------------------------------------
-// Unsigned
-// ------------------------------------------------------------------------
-
-/**
-  Reads an 8-bit unsigned int from the stream.
-  @return {number} The read number.
- */
-KaitaiStream.prototype.readU1 = function() {
-  this.ensureBytesLeft(1);
-  var v = this._dataView.getUint8(this.pos);
-  this.pos += 1;
-  return v;
-};
-
-// ........................................................................
-// Big-endian
-// ........................................................................
-
-/**
-  Reads a 16-bit big-endian unsigned int from the stream.
-  @return {number} The read number.
- */
-KaitaiStream.prototype.readU2be = function() {
-  this.ensureBytesLeft(2);
-  var v = this._dataView.getUint16(this.pos);
-  this.pos += 2;
-  return v;
-};
-
-/**
-  Reads a 32-bit big-endian unsigned int from the stream.
-  @return {number} The read number.
- */
-KaitaiStream.prototype.readU4be = function() {
-  this.ensureBytesLeft(4);
-  var v = this._dataView.getUint32(this.pos);
-  this.pos += 4;
-  return v;
-};
-
-/**
-  Reads a 64-bit big-endian unsigned int from the stream. Note that
-  JavaScript does not support 64-bit integers natively, so it will
-  automatically upgrade internal representation to use IEEE 754
-  double precision float.
-  @return {number} The read number.
- */
-KaitaiStream.prototype.readU8be = function() {
-  this.ensureBytesLeft(8);
-  var v1 = this.readU4be();
-  var v2 = this.readU4be();
-  return 0x100000000 * v1 + v2;
-};
-
-// ........................................................................
-// Little-endian
-// ........................................................................
-
-/**
-  Reads a 16-bit little-endian unsigned int from the stream.
-  @return {number} The read number.
- */
-KaitaiStream.prototype.readU2le = function() {
-  this.ensureBytesLeft(2);
-  var v = this._dataView.getUint16(this.pos, true);
-  this.pos += 2;
-  return v;
-};
-
-/**
-  Reads a 32-bit little-endian unsigned int from the stream.
-  @return {number} The read number.
- */
-KaitaiStream.prototype.readU4le = function() {
-  this.ensureBytesLeft(4);
-  var v = this._dataView.getUint32(this.pos, true);
-  this.pos += 4;
-  return v;
-};
-
-/**
-  Reads a 64-bit little-endian unsigned int from the stream. Note that
-  JavaScript does not support 64-bit integers natively, so it will
-  automatically upgrade internal representation to use IEEE 754
-  double precision float.
-  @return {number} The read number.
- */
-KaitaiStream.prototype.readU8le = function() {
-  this.ensureBytesLeft(8);
-  var v1 = this.readU4le();
-  var v2 = this.readU4le();
-  return 0x100000000 * v2 + v1;
-};
-
-// ========================================================================
-// Floating point numbers
-// ========================================================================
-
-// ------------------------------------------------------------------------
-// Big endian
-// ------------------------------------------------------------------------
-
-KaitaiStream.prototype.readF4be = function() {
-  this.ensureBytesLeft(4);
-  var v = this._dataView.getFloat32(this.pos);
-  this.pos += 4;
-  return v;
-};
-
-KaitaiStream.prototype.readF8be = function() {
-  this.ensureBytesLeft(8);
-  var v = this._dataView.getFloat64(this.pos);
-  this.pos += 8;
-  return v;
-};
-
-// ------------------------------------------------------------------------
-// Little endian
-// ------------------------------------------------------------------------
-
-KaitaiStream.prototype.readF4le = function() {
-  this.ensureBytesLeft(4);
-  var v = this._dataView.getFloat32(this.pos, true);
-  this.pos += 4;
-  return v;
-};
-
-KaitaiStream.prototype.readF8le = function() {
-  this.ensureBytesLeft(8);
-  var v = this._dataView.getFloat64(this.pos, true);
-  this.pos += 8;
-  return v;
-};
-
-// ------------------------------------------------------------------------
-// Unaligned bit values
-// ------------------------------------------------------------------------
-
-KaitaiStream.prototype.alignToByte = function() {
-  this.bitsLeft = 0;
-  this.bits = 0;
-};
-
-/*
- bitsLeft = 3
-      \  \  bitsNeeded = 10 -> bytesNeeded = 2
-       \  \ /         \
-  |01101xxx|xxxxxxxx|xx......|
-        \             /\     \
-         \__ n = 13 _/  \     \
-                       new bitsLeft = 6
- */
-KaitaiStream.prototype.readBitsIntBe = function(n) {
-  // JS only supports bit operations on 32 bits
-  if (n > 32) {
-    throw new RangeError("readBitsIntBe: the maximum supported bit length is 32 (tried to read " + n + " bits)");
-  }
-  var res = 0;
-
-  var bitsNeeded = n - this.bitsLeft;
-  this.bitsLeft = -bitsNeeded & 7; // `-bitsNeeded mod 8`
-
-  if (bitsNeeded > 0) {
-    // 1 bit  => 1 byte
-    // 8 bits => 1 byte
-    // 9 bits => 2 bytes
-    var bytesNeeded = ((bitsNeeded - 1) >> 3) + 1; // `ceil(bitsNeeded / 8)` (NB: `x >> 3` is `floor(x / 8)`)
-    var buf = this.readBytes(bytesNeeded);
-    for (var i = 0; i < bytesNeeded; i++) {
-      res = res << 8 | buf[i];
-    }
-
-    var newBits = res;
-    res = res >>> this.bitsLeft | this.bits << bitsNeeded; // `x << 32` is defined as `x << 0` in JS, but only `0 << 32`
-                                                           // can occur here (`n = 32` and `bitsLeft = 0`, this implies
-                                                           // `bits = 0` unless changed externally)
-    this.bits = newBits; // will be masked at the end of the function
-  } else {
-    res = this.bits >>> -bitsNeeded; // shift unneeded bits out
-  }
-
-  var mask = (1 << this.bitsLeft) - 1; // `bitsLeft` is in range 0..7, so `(1 << 32)` does not have to be considered
-  this.bits &= mask;
-
-  // always return an unsigned 32-bit integer
-  return res >>> 0;
-};
-
-/**
- * Unused since Kaitai Struct Compiler v0.9+ - compatibility with older versions
- *
- * @deprecated use {@link readBitsIntBe} instead
- */
-KaitaiStream.prototype.readBitsInt = KaitaiStream.prototype.readBitsIntBe;
-
-/*
-    n = 13       bitsNeeded = 10
-                    /       \
- bitsLeft = 3  ______       __
-    \  \      /      \      \ \
-    |xxx01101|xxxxxxxx|......xx|
-                       \    /
-                    new bitsLeft = 6
-
-          bitsLeft = 7
-             \      \
-    |01101100|..xxxxx1|........|
-                \___/
-                n = 5
- */
-KaitaiStream.prototype.readBitsIntLe = function(n) {
-  // JS only supports bit operations on 32 bits
-  if (n > 32) {
-    throw new RangeError("readBitsIntLe: the maximum supported bit length is 32 (tried to read " + n + " bits)");
-  }
-  var res = 0;
-  var bitsNeeded = n - this.bitsLeft;
-
-  if (bitsNeeded > 0) {
-    // 1 bit  => 1 byte
-    // 8 bits => 1 byte
-    // 9 bits => 2 bytes
-    var bytesNeeded = ((bitsNeeded - 1) >> 3) + 1; // `ceil(bitsNeeded / 8)` (NB: `x >> 3` is `floor(x / 8)`)
-    var buf = this.readBytes(bytesNeeded);
-    for (var i = 0; i < bytesNeeded; i++) {
-      res |= buf[i] << (i * 8);
-    }
-
-    // NB: in JavaScript, bit shift operators always shift by modulo 32 of the right-hand operand (see
-    // https://tc39.es/ecma262/multipage/ecmascript-data-types-and-values.html#sec-numeric-types-number-unsignedRightShift),
-    // so `res >>> 32` is equivalent to `res >>> 0` (but we don't want that)
-    var newBits = bitsNeeded < 32 ? res >>> bitsNeeded : 0;
-    res = res << this.bitsLeft | this.bits;
-    this.bits = newBits;
-  } else {
-    res = this.bits;
-    this.bits >>>= n;
-  }
-
-  this.bitsLeft = -bitsNeeded & 7; // `-bitsNeeded mod 8`
-
-  // always return an unsigned 32-bit integer
-  if (n < 32) {
-    var mask = (1 << n) - 1;
-    res &= mask; // this produces a signed 32-bit int, but the sign bit is cleared
-  } else {
-    res >>>= 0;
-  }
-  return res;
-};
-
-/**
-  Native endianness. Either KaitaiStream.BIG_ENDIAN or KaitaiStream.LITTLE_ENDIAN
-  depending on the platform endianness.
-
-  @type {boolean}
- */
-KaitaiStream.endianness = new Int8Array(new Int16Array([1]).buffer)[0] > 0;
-
-// ========================================================================
-// Byte arrays
-// ========================================================================
-
-KaitaiStream.prototype.readBytes = function(len) {
-  return this.mapUint8Array(len);
-};
-
-KaitaiStream.prototype.readBytesFull = function() {
-  return this.mapUint8Array(this.size - this.pos);
-};
-
-KaitaiStream.prototype.readBytesTerm = function(terminator, include, consume, eosError) {
-  var blen = this.size - this.pos;
-  var u8 = new Uint8Array(this._buffer, this._byteOffset + this.pos);
-  for (var i = 0; i < blen && u8[i] !== terminator; i++); // find first zero byte
-  if (i === blen) {
-    // we've read all the buffer and haven't found the terminator
-    if (eosError) {
-      throw "End of stream reached, but no terminator " + terminator + " found";
-    } else {
-      return this.mapUint8Array(i);
-    }
-  } else {
-    var arr;
-    if (include) {
-      arr = this.mapUint8Array(i + 1);
-    } else {
-      arr = this.mapUint8Array(i);
-    }
-    if (consume) {
-      this.pos += 1;
-    }
-    return arr;
-  }
-};
-
-KaitaiStream.prototype.readBytesTermMulti = function(terminator, include, consume, eosError) {
-  var unitSize = terminator.length;
-  var data = new Uint8Array(this._buffer, this._byteOffset + this.pos, this.size - this.pos);
-  var res = KaitaiStream.bytesTerminateMulti(data, terminator, true);
-  this.pos += res.length;
-  var termFound =
-    res.length !== 0 &&
-    res.length % unitSize === 0 &&
-    KaitaiStream.byteArrayCompare(new Uint8Array(res.buffer, res.length - unitSize), terminator) === 0;
-  if (termFound) {
-    if (!include) {
-      res = new Uint8Array(res.buffer, res.byteOffset, res.length - unitSize);
-    }
-    if (!consume) {
-      this.pos -= unitSize;
-    }
-  } else if (eosError) {
-    throw new Error("End of stream reached, but no terminator " + terminator + " found");
-  }
-  return res;
-};
-
-// Unused since Kaitai Struct Compiler v0.9+ - compatibility with older versions
-KaitaiStream.prototype.ensureFixedContents = function(expected) {
-  var actual = this.readBytes(expected.length);
-  if (actual.length !== expected.length) {
-    throw new UnexpectedDataError(expected, actual);
-  }
-  var actLen = actual.length;
-  for (var i = 0; i < actLen; i++) {
-    if (actual[i] !== expected[i]) {
-      throw new UnexpectedDataError(expected, actual);
-    }
-  }
-  return actual;
-};
-
-KaitaiStream.bytesStripRight = function(data, padByte) {
-  var newLen = data.length;
-  while (data[newLen - 1] === padByte) {
-    newLen--;
-  }
-  return data.slice(0, newLen);
-};
-
-KaitaiStream.bytesTerminate = function(data, term, include) {
-  var newLen = 0;
-  var maxLen = data.length;
-  while (newLen < maxLen && data[newLen] !== term) {
-    newLen++;
-  }
-  if (include && newLen < maxLen)
-    newLen++;
-  return data.slice(0, newLen);
-};
-
-KaitaiStream.bytesTerminateMulti = function(data, term, include) {
-  var unitSize = term.length;
-  if (unitSize === 0) {
-    return new Uint8Array();
-  }
-  var len = data.length;
-  var iTerm = 0;
-  for (var iData = 0; iData < len;) {
-    if (data[iData] !== term[iTerm]) {
-      iData += unitSize - iTerm;
-      iTerm = 0;
-      continue;
-    }
-    iData++;
-    iTerm++;
-    if (iTerm === unitSize) {
-      return data.slice(0, iData - (include ? 0 : unitSize));
-    }
-  }
-  return data.slice();
-};
-
-KaitaiStream.bytesToStr = function(arr, encoding) {
-  if (encoding == null || encoding.toLowerCase() === "ascii") {
-    return KaitaiStream.createStringFromArray(arr);
-  } else {
-    if (typeof TextDecoder === 'function') {
-      // we're in the browser that supports TextDecoder
-      return (new TextDecoder(encoding)).decode(arr);
-    } else {
-      // probably we're in node.js
-
-      // check if it's supported natively by node.js Buffer
-      // see https://github.com/nodejs/node/blob/master/lib/buffer.js#L187 for details
-      switch (encoding.toLowerCase()) {
-        case 'utf8':
-        case 'utf-8':
-        case 'ucs2':
-        case 'ucs-2':
-        case 'utf16le':
-        case 'utf-16le':
-          return new Buffer(arr).toString(encoding);
-          break;
-        default:
-          // unsupported encoding, we'll have to resort to iconv-lite
-          if (typeof KaitaiStream.iconvlite === 'undefined')
-            KaitaiStream.iconvlite = require('iconv-lite');
-
-          return KaitaiStream.iconvlite.decode(arr, encoding);
-      }
-    }
-  }
-};
-
-// ========================================================================
-// Byte array processing
-// ========================================================================
-
-KaitaiStream.processXorOne = function(data, key) {
-  var r = new Uint8Array(data.length);
-  var dl = data.length;
-  for (var i = 0; i < dl; i++)
-    r[i] = data[i] ^ key;
-  return r;
-};
-
-KaitaiStream.processXorMany = function(data, key) {
-  var dl = data.length;
-  var r = new Uint8Array(dl);
-  var kl = key.length;
-  var ki = 0;
-  for (var i = 0; i < dl; i++) {
-    r[i] = data[i] ^ key[ki];
-    ki++;
-    if (ki >= kl)
-      ki = 0;
-  }
-  return r;
-};
-
-KaitaiStream.processRotateLeft = function(data, amount, groupSize) {
-  if (groupSize !== 1)
-    throw("unable to rotate group of " + groupSize + " bytes yet");
-
-  var mask = groupSize * 8 - 1;
-  var antiAmount = -amount & mask;
-
-  var r = new Uint8Array(data.length);
-  for (var i = 0; i < data.length; i++)
-    r[i] = (data[i] << amount) & 0xff | (data[i] >> antiAmount);
-
-  return r;
-};
-
-KaitaiStream.processZlib = function(buf) {
-  if (typeof require !== 'undefined')  {
-    // require is available - we're running under node
-    if (typeof KaitaiStream.zlib === 'undefined')
-      KaitaiStream.zlib = require('zlib');
-    // use node's zlib module API
-    var r = KaitaiStream.zlib.inflateSync(
-      Buffer.from(buf.buffer.slice(buf.byteOffset, buf.byteOffset + buf.byteLength))
-    );
-    return r;
-  } else {
-    // no require() - assume we're running as a web worker in browser.
-    // user should have configured KaitaiStream.depUrls.zlib, if not
-    // we'll throw.
-    if (typeof KaitaiStream.zlib === 'undefined'
-      && typeof KaitaiStream.depUrls.zlib !== 'undefined') {
-      importScripts(KaitaiStream.depUrls.zlib);
-      KaitaiStream.zlib = pako;
-    }
-    // use pako API
-    r = KaitaiStream.zlib.inflate(buf);
-    return r;
-  }
-};
-
-// ========================================================================
-// Misc runtime operations
-// ========================================================================
-
-KaitaiStream.mod = function(a, b) {
-  if (b <= 0)
-    throw "mod divisor <= 0";
-  var r = a % b;
-  if (r < 0)
-    r += b;
-  return r;
-};
-
-KaitaiStream.arrayMin = function(arr) {
-  var min = arr[0];
-  var x;
-  for (var i = 1, n = arr.length; i < n; ++i) {
-    x = arr[i];
-    if (x < min) min = x;
-  }
-  return min;
-};
-
-KaitaiStream.arrayMax = function(arr) {
-  var max = arr[0];
-  var x;
-  for (var i = 1, n = arr.length; i < n; ++i) {
-    x = arr[i];
-    if (x > max) max = x;
-  }
-  return max;
-};
-
-KaitaiStream.byteArrayCompare = function(a, b) {
-  if (a === b)
-    return 0;
-  var al = a.length;
-  var bl = b.length;
-  var minLen = al < bl ? al : bl;
-  for (var i = 0; i < minLen; i++) {
-    var cmp = a[i] - b[i];
-    if (cmp !== 0)
-      return cmp;
-  }
-
-  // Reached the end of at least one of the arrays
-  if (al === bl) {
-    return 0;
-  } else {
-    return al - bl;
-  }
-};
-
-// ========================================================================
-// Internal implementation details
-// ========================================================================
-
-var EOFError = KaitaiStream.EOFError = function(bytesReq, bytesAvail) {
-  this.name = "EOFError";
-  this.message = "requested " + bytesReq + " bytes, but only " + bytesAvail + " bytes available";
-  this.bytesReq = bytesReq;
-  this.bytesAvail = bytesAvail;
-  this.stack = (new Error()).stack;
-};
-
-EOFError.prototype = Object.create(Error.prototype);
-EOFError.prototype.constructor = EOFError;
-
-// Unused since Kaitai Struct Compiler v0.9+ - compatibility with older versions
-var UnexpectedDataError = KaitaiStream.UnexpectedDataError = function(expected, actual) {
-  this.name = "UnexpectedDataError";
-  this.message = "expected [" + expected + "], but got [" + actual + "]";
-  this.expected = expected;
-  this.actual = actual;
-  this.stack = (new Error()).stack;
-};
-
-UnexpectedDataError.prototype = Object.create(Error.prototype);
-UnexpectedDataError.prototype.constructor = UnexpectedDataError;
-
-var UndecidedEndiannessError = KaitaiStream.UndecidedEndiannessError = function() {
-  this.name = "UndecidedEndiannessError";
-  this.stack = (new Error()).stack;
-};
-
-UndecidedEndiannessError.prototype = Object.create(Error.prototype);
-UndecidedEndiannessError.prototype.constructor = UndecidedEndiannessError;
-
-var ValidationNotEqualError = KaitaiStream.ValidationNotEqualError = function(expected, actual) {
-  this.name = "ValidationNotEqualError";
-  this.message = "not equal, expected [" + expected + "], but got [" + actual + "]";
-  this.expected = expected;
-  this.actual = actual;
-  this.stack = (new Error()).stack;
-};
-
-ValidationNotEqualError.prototype = Object.create(Error.prototype);
-ValidationNotEqualError.prototype.constructor = ValidationNotEqualError;
-
-var ValidationLessThanError = KaitaiStream.ValidationLessThanError = function(min, actual) {
-  this.name = "ValidationLessThanError";
-  this.message = "not in range, min [" + min + "], but got [" + actual + "]";
-  this.min = min;
-  this.actual = actual;
-  this.stack = (new Error()).stack;
-};
-
-ValidationLessThanError.prototype = Object.create(Error.prototype);
-ValidationLessThanError.prototype.constructor = ValidationLessThanError;
-
-var ValidationGreaterThanError = KaitaiStream.ValidationGreaterThanError = function(max, actual) {
-  this.name = "ValidationGreaterThanError";
-  this.message = "not in range, max [" + max + "], but got [" + actual + "]";
-  this.max = max;
-  this.actual = actual;
-  this.stack = (new Error()).stack;
-};
-
-ValidationGreaterThanError.prototype = Object.create(Error.prototype);
-ValidationGreaterThanError.prototype.constructor = ValidationGreaterThanError;
-
-var ValidationNotAnyOfError = KaitaiStream.ValidationNotAnyOfError = function(actual, io, srcPath) {
-  this.name = "ValidationNotAnyOfError";
-  this.message = "not any of the list, got [" + actual + "]";
-  this.actual = actual;
-  this.stack = (new Error()).stack;
-};
-
-ValidationNotAnyOfError.prototype = Object.create(Error.prototype);
-ValidationNotAnyOfError.prototype.constructor = ValidationNotAnyOfError;
-
-var ValidationNotInEnumError = KaitaiStream.ValidationNotInEnumError = function(actual, io, srcPath) {
-  this.name = "ValidationNotInEnumError";
-  this.message = "not in the enum, got [" + actual + "]";
-  this.actual = actual;
-  this.stack = (new Error()).stack;
-};
-
-ValidationNotInEnumError.prototype = Object.create(Error.prototype);
-ValidationNotInEnumError.prototype.constructor = ValidationNotInEnumError;
-
-var ValidationExprError = KaitaiStream.ValidationExprError = function(actual, io, srcPath) {
-  this.name = "ValidationExprError";
-  this.message = "not matching the expression, got [" + actual + "]";
-  this.actual = actual;
-  this.stack = (new Error()).stack;
-};
-
-ValidationExprError.prototype = Object.create(Error.prototype);
-ValidationExprError.prototype.constructor = ValidationExprError;
-
-/**
-  Ensures that we have an least `length` bytes left in the stream.
-  If that's not true, throws an EOFError.
-
-  @param {number} length Number of bytes to require
-  */
-KaitaiStream.prototype.ensureBytesLeft = function(length) {
-  if (this.pos + length > this.size) {
-    throw new EOFError(length, this.size - this.pos);
-  }
-};
-
-/**
-  Maps a Uint8Array into the KaitaiStream buffer.
-
-  Nice for quickly reading in data.
-
-  @param {number} length Number of elements to map.
-  @return {Object} Uint8Array to the KaitaiStream backing buffer.
-  */
-KaitaiStream.prototype.mapUint8Array = function(length) {
-  length |= 0;
-
-  this.ensureBytesLeft(length);
-
-  var arr = new Uint8Array(this._buffer, this.byteOffset + this.pos, length);
-  this.pos += length;
-  return arr;
-};
-
-/**
-  Creates an array from an array of character codes.
-  Uses String.fromCharCode in chunks for memory efficiency and then concatenates
-  the resulting string chunks.
-
-  @param {array|Uint8Array} array Array of character codes.
-  @return {string} String created from the character codes.
-**/
-KaitaiStream.createStringFromArray = function(array) {
-  var chunk_size = 0x8000;
-  var chunks = [];
-  var useSubarray = typeof array.subarray === 'function';
-  for (var i=0; i < array.length; i += chunk_size) {
-    chunks.push(String.fromCharCode.apply(null, useSubarray ? array.subarray(i, i + chunk_size) : array.slice(i, i + chunk_size)));
-  }
-  return chunks.join("");
-};
-
-return KaitaiStream;
-
-}));
diff --git a/KaitaiStream.ts b/KaitaiStream.ts
new file mode 100644
index 0000000..a53a11e
--- /dev/null
+++ b/KaitaiStream.ts
@@ -0,0 +1,1154 @@
+// -*- mode: js; js-indent-level: 2; -*-
+
+// Interfaces for optional dependencies
+interface IconvLite {
+  decode(buffer: Buffer | Uint8Array, encoding: string): string
+}
+
+interface Zlib {
+  inflateSync(buf: ArrayBuffer | NodeJS.ArrayBufferView): Buffer;
+}
+
+interface Pako {
+  inflate(data: Uint8Array | number[]): Uint8Array;
+}
+
+// Workaround for https://github.com/microsoft/TypeScript/issues/36470
+declare global {
+  interface CallableFunction {
+    apply<T, A, R>(this: (this: T, ...args: A[]) => R, thisArg: T, args: ArrayLike<A>): R;
+  }
+}
+
+// When loaded into a web worker, pako gets added to the global scope
+declare const pako: Pako;
+
+/**
+ * KaitaiStream is an implementation of Kaitai Struct API for JavaScript.
+ * Based on DataStream - https://github.com/kig/DataStream.js .
+ */
+class KaitaiStream {
+  /**
+   * @param arrayBuffer ArrayBuffer to read from.
+   * @param byteOffset Offset from arrayBuffer beginning for the KaitaiStream.
+   */
+  public constructor(arrayBuffer: ArrayBuffer | DataView | number, byteOffset?: number) {
+    this._byteOffset = byteOffset || 0;
+    if (arrayBuffer instanceof ArrayBuffer) {
+      this.buffer = arrayBuffer;
+    } else if (typeof arrayBuffer == "object") {
+      this.dataView = arrayBuffer;
+      if (byteOffset) {
+        this._byteOffset += byteOffset;
+      }
+    } else {
+      this.buffer = new ArrayBuffer(arrayBuffer || 1);
+    }
+    this.pos = 0;
+    this.alignToByte();
+  }
+
+  /**
+   * Virtual byte length of the KaitaiStream backing buffer.
+   * Updated to be max of original buffer size and last written size.
+   * If dynamicSize is false is set to buffer size.
+   */
+  private _byteLength = 0;
+  private _byteOffset = 0;
+  private _buffer!: ArrayBuffer;
+  private _dataView!: DataView;
+
+  public pos: number;
+  public bits = 0;
+  public bitsLeft = 0;
+
+  /**
+   * Dependency configuration data. Holds urls for (optional) dynamic loading
+   * of code dependencies from a remote server. For use by (static) processing functions.
+   *
+   * Caller should the supported keys to the asset urls as needed.
+   * NOTE: `depUrls` is a static property of KaitaiStream (the factory), like the various
+   * processing functions. It is NOT part of the prototype of instances.
+   */
+  public static depUrls: Record<string, string | undefined> = {
+    // processZlib uses this and expected a link to a copy of pako.
+    // specifically the pako_inflate.min.js script at:
+    // https://raw.githubusercontent.com/nodeca/pako/master/dist/pako_inflate.min.js
+    zlib: undefined
+  };
+
+  public static iconvlite?: IconvLite;
+  public static zlib?: Pako | Zlib;
+
+  /**
+   * Gets the backing ArrayBuffer of the KaitaiStream object.
+   *
+   * @returns The backing ArrayBuffer.
+   */
+  public get buffer(): ArrayBuffer {
+    this._trimAlloc();
+    return this._buffer;
+  }
+
+  /**
+   * Sets the backing ArrayBuffer of the KaitaiStream object and updates the
+   * DataView to point to the new buffer.
+   */
+  public set buffer(v: ArrayBuffer) {
+    this._buffer = v;
+    this._dataView = new DataView(this._buffer, this._byteOffset);
+    this._byteLength = this._buffer.byteLength;
+  }
+
+  /**
+   * Gets the byteOffset of the KaitaiStream object.
+   *
+   * @returns The byteOffset.
+   */
+  public get byteOffset(): number {
+    return this._byteOffset;
+  }
+
+  /**
+   * Sets the byteOffset of the KaitaiStream object and updates the DataView to
+   * point to the new byteOffset.
+   */
+  public set byteOffset(v: number) {
+    this._byteOffset = v;
+    this._dataView = new DataView(this._buffer, this._byteOffset);
+    this._byteLength = this._buffer.byteLength;
+  }
+
+  /**
+   * Gets the backing DataView of the KaitaiStream object.
+   *
+   * @returns The backing DataView.
+   */
+  public get dataView(): DataView {
+    return this._dataView;
+  }
+  /**
+   * Sets the backing DataView of the KaitaiStream object and updates the buffer
+   * and byteOffset to point to the DataView values.
+   */
+  public set dataView(v: DataView) {
+    this._byteOffset = v.byteOffset;
+    this._buffer = v.buffer;
+    this._dataView = new DataView(this._buffer, this._byteOffset);
+    this._byteLength = this._byteOffset + v.byteLength;
+  }
+
+  /**
+   * Internal function to trim the KaitaiStream buffer when required.
+   * Used for stripping out the extra bytes from the backing buffer when
+   * the virtual byteLength is smaller than the buffer byteLength (happens after
+   * growing the buffer with writes and not filling the extra space completely).
+   */
+  private _trimAlloc(): void {
+    if (this._byteLength === this._buffer.byteLength) {
+      return;
+    }
+    const buf = new ArrayBuffer(this._byteLength);
+    const dst = new Uint8Array(buf);
+    const src = new Uint8Array(this._buffer, 0, dst.length);
+    dst.set(src);
+    this.buffer = buf;
+  }
+
+  // ========================================================================
+  // Stream positioning
+  // ========================================================================
+
+  /**
+   * Returns true if the KaitaiStream seek pointer is at the end of buffer and
+   * there's no more data to read.
+   *
+   * @returns True if the seek pointer is at the end of the buffer.
+   */
+  public isEof(): boolean {
+    return this.pos >= this.size && this.bitsLeft === 0;
+  }
+
+  /**
+   * Sets the KaitaiStream read/write position to given position.
+   * Clamps between 0 and KaitaiStream length.
+   *
+   * @param pos Position to seek to.
+   */
+  public seek(pos: number): void {
+    const npos = Math.max(0, Math.min(this.size, pos));
+    this.pos = (isNaN(npos) || !isFinite(npos)) ? 0 : npos;
+  }
+
+  /**
+   * Returns the byte length of the KaitaiStream object.
+   *
+   * @returns The byte length.
+   */
+  public get size(): number {
+    return this._byteLength - this._byteOffset;
+  }
+
+  // ========================================================================
+  // Integer numbers
+  // ========================================================================
+
+  // ------------------------------------------------------------------------
+  // Signed
+  // ------------------------------------------------------------------------
+
+  /**
+   * Reads an 8-bit signed int from the stream.
+   *
+   * @returns The read number.
+   */
+  public readS1(): number {
+    this.ensureBytesLeft(1);
+    const v = this._dataView.getInt8(this.pos);
+    this.pos += 1;
+    return v;
+  }
+
+  // ........................................................................
+  // Big-endian
+  // ........................................................................
+
+  /**
+   * Reads a 16-bit big-endian signed int from the stream.
+   *
+   * @returns The read number.
+   */
+  public readS2be(): number {
+    this.ensureBytesLeft(2);
+    const v = this._dataView.getInt16(this.pos);
+    this.pos += 2;
+    return v;
+  }
+
+  /**
+   * Reads a 32-bit big-endian signed int from the stream.
+   *
+   * @returns The read number.
+   */
+  public readS4be(): number {
+    this.ensureBytesLeft(4);
+    const v = this._dataView.getInt32(this.pos);
+    this.pos += 4;
+    return v;
+  }
+
+  /**
+   * Reads a 64-bit big-endian unsigned int from the stream. Note that
+   * JavaScript does not support 64-bit integers natively, so it will
+   * automatically upgrade internal representation to use IEEE 754
+   * double precision float.
+   *
+   * @returns The read number.
+   */
+  public readS8be(): number {
+    this.ensureBytesLeft(8);
+    const v1 = this.readU4be();
+    const v2 = this.readU4be();
+
+    if ((v1 & 0x80000000) !== 0) {
+      // negative number
+      return -(0x100000000 * (v1 ^ 0xffffffff) + (v2 ^ 0xffffffff)) - 1;
+    } else {
+      return 0x100000000 * v1 + v2;
+    }
+  }
+
+  // ........................................................................
+  // Little-endian
+  // ........................................................................
+
+  /**
+   * Reads a 16-bit little-endian signed int from the stream.
+   *
+   * @returns The read number.
+   */
+  public readS2le(): number {
+    this.ensureBytesLeft(2);
+    const v = this._dataView.getInt16(this.pos, true);
+    this.pos += 2;
+    return v;
+  }
+
+  /**
+   * Reads a 32-bit little-endian signed int from the stream.
+   *
+   * @returns The read number.
+   */
+  public readS4le(): number {
+    this.ensureBytesLeft(4);
+    const v = this._dataView.getInt32(this.pos, true);
+    this.pos += 4;
+    return v;
+  }
+
+  /**
+   * Reads a 64-bit little-endian unsigned int from the stream. Note that
+   * JavaScript does not support 64-bit integers natively, so it will
+   * automatically upgrade internal representation to use IEEE 754
+   * double precision float.
+   *
+   * @returns The read number.
+   */
+  public readS8le(): number {
+    this.ensureBytesLeft(8);
+    const v1 = this.readU4le();
+    const v2 = this.readU4le();
+
+    if ((v2 & 0x80000000) !== 0) {
+      // negative number
+      return -(0x100000000 * (v2 ^ 0xffffffff) + (v1 ^ 0xffffffff)) - 1;
+    } else {
+      return 0x100000000 * v2 + v1;
+    }
+  }
+
+  // ------------------------------------------------------------------------
+  // Unsigned
+  // ------------------------------------------------------------------------
+
+  /**
+   * Reads an 8-bit unsigned int from the stream.
+   *
+   * @returns The read number.
+   */
+  public readU1(): number {
+    this.ensureBytesLeft(1);
+    const v = this._dataView.getUint8(this.pos);
+    this.pos += 1;
+    return v;
+  }
+
+  // ........................................................................
+  // Big-endian
+  // ........................................................................
+
+  /**
+   * Reads a 16-bit big-endian unsigned int from the stream.
+   *
+   * @returns The read number.
+   */
+  public readU2be(): number {
+    this.ensureBytesLeft(2);
+    const v = this._dataView.getUint16(this.pos);
+    this.pos += 2;
+    return v;
+  }
+
+  /**
+   * Reads a 32-bit big-endian unsigned int from the stream.
+   *
+   * @returns The read number.
+   */
+  public readU4be(): number {
+    this.ensureBytesLeft(4);
+    const v = this._dataView.getUint32(this.pos);
+    this.pos += 4;
+    return v;
+  }
+
+  /**
+   * Reads a 64-bit big-endian unsigned int from the stream. Note that
+   * JavaScript does not support 64-bit integers natively, so it will
+   * automatically upgrade internal representation to use IEEE 754
+   * double precision float.
+   *
+   * @returns The read number.
+   */
+  public readU8be(): number {
+    this.ensureBytesLeft(8);
+    const v1 = this.readU4be();
+    const v2 = this.readU4be();
+    return 0x100000000 * v1 + v2;
+  }
+
+  // ........................................................................
+  // Little-endian
+  // ........................................................................
+
+  /**
+   * Reads a 16-bit little-endian unsigned int from the stream.
+   *
+   * @returns The read number.
+   */
+  public readU2le(): number {
+    this.ensureBytesLeft(2);
+    const v = this._dataView.getUint16(this.pos, true);
+    this.pos += 2;
+    return v;
+  }
+
+  /**
+   * Reads a 32-bit little-endian unsigned int from the stream.
+   *
+   * @returns The read number.
+   */
+  public readU4le(): number {
+    this.ensureBytesLeft(4);
+    const v = this._dataView.getUint32(this.pos, true);
+    this.pos += 4;
+    return v;
+  }
+
+  /**
+   * Reads a 64-bit little-endian unsigned int from the stream. Note that
+   * JavaScript does not support 64-bit integers natively, so it will
+   * automatically upgrade internal representation to use IEEE 754
+   * double precision float.
+   *
+   * @returns The read number.
+   */
+  public readU8le(): number {
+    this.ensureBytesLeft(8);
+    const v1 = this.readU4le();
+    const v2 = this.readU4le();
+    return 0x100000000 * v2 + v1;
+  }
+
+  // ========================================================================
+  // Floating point numbers
+  // ========================================================================
+
+  // ------------------------------------------------------------------------
+  // Big endian
+  // ------------------------------------------------------------------------
+
+  /**
+   * Reads a 32-bit big-endian float from the stream.
+   *
+   * @returns The read number.
+   */
+  public readF4be(): number {
+    this.ensureBytesLeft(4);
+    const v = this._dataView.getFloat32(this.pos);
+    this.pos += 4;
+    return v;
+  }
+
+  /**
+   * Reads a 64-bit big-endian float from the stream.
+   *
+   * @returns The read number.
+   */
+  public readF8be(): number {
+    this.ensureBytesLeft(8);
+    const v = this._dataView.getFloat64(this.pos);
+    this.pos += 8;
+    return v;
+  }
+
+  // ------------------------------------------------------------------------
+  // Little endian
+  // ------------------------------------------------------------------------
+
+  /**
+   * Reads a 32-bit little-endian float from the stream.
+   *
+   * @returns The read number.
+   */
+  public readF4le(): number {
+    this.ensureBytesLeft(4);
+    const v = this._dataView.getFloat32(this.pos, true);
+    this.pos += 4;
+    return v;
+  }
+
+  /**
+   * Reads a 64-bit little-endian float from the stream.
+   *
+   * @returns The read number.
+   */
+  public readF8le(): number {
+    this.ensureBytesLeft(8);
+    const v = this._dataView.getFloat64(this.pos, true);
+    this.pos += 8;
+    return v;
+  }
+
+  // ------------------------------------------------------------------------
+  // Unaligned bit values
+  // ------------------------------------------------------------------------
+
+  /**
+   * Aligns the stream position to the next byte boundary.
+   */
+  public alignToByte(): void {
+    this.bitsLeft = 0;
+    this.bits = 0;
+  }
+
+  /**
+   * @param n The number of bits to read.
+   * @returns The read bits.
+   * @throws {RangeError}
+   */
+  public readBitsIntBe(n: number): number {
+    // JS only supports bit operations on 32 bits
+    if (n > 32) {
+      throw new RangeError("readBitsIntBe: the maximum supported bit length is 32 (tried to read " + n + " bits)");
+    }
+    let res = 0;
+
+    const bitsNeeded = n - this.bitsLeft;
+    this.bitsLeft = -bitsNeeded & 7; // `-bitsNeeded mod 8`
+
+    if (bitsNeeded > 0) {
+      // 1 bit  => 1 byte
+      // 8 bits => 1 byte
+      // 9 bits => 2 bytes
+      const bytesNeeded = ((bitsNeeded - 1) >> 3) + 1; // `ceil(bitsNeeded / 8)` (NB: `x >> 3` is `floor(x / 8)`)
+      const buf = this.readBytes(bytesNeeded);
+      for (let i = 0; i < bytesNeeded; i++) {
+        res = res << 8 | buf[i];
+      }
+
+      const newBits = res;
+      res = res >>> this.bitsLeft | this.bits << bitsNeeded; // `x << 32` is defined as `x << 0` in JS, but only `0 << 32`
+                                                            // can occur here (`n = 32` and `bitsLeft = 0`, this implies
+                                                            // `bits = 0` unless changed externally)
+      this.bits = newBits; // will be masked at the end of the function
+    } else {
+      res = this.bits >>> -bitsNeeded; // shift unneeded bits out
+    }
+
+    const mask = (1 << this.bitsLeft) - 1; // `bitsLeft` is in range 0..7, so `(1 << 32)` does not have to be considered
+    this.bits &= mask;
+
+    // always return an unsigned 32-bit integer
+    return res >>> 0;
+  }
+
+  /**
+   * Unused since Kaitai Struct Compiler v0.9+ - compatibility with older versions.
+   *
+   * @deprecated Use {@link readBitsIntBe} instead.
+   * @param n The number of bits to read.
+   * @returns The read bits.
+   */
+  public readBitsInt(n: number): number {
+    return this.readBitsIntBe(n);
+  }
+
+  /**
+   * @param n The number of bits to read.
+   * @returns The read bits.
+   * @throws {RangeError}
+   */
+  public readBitsIntLe(n: number): number {
+    // JS only supports bit operations on 32 bits
+    if (n > 32) {
+      throw new RangeError("readBitsIntLe: the maximum supported bit length is 32 (tried to read " + n + " bits)");
+    }
+    let res = 0;
+    const bitsNeeded = n - this.bitsLeft;
+
+    if (bitsNeeded > 0) {
+      // 1 bit  => 1 byte
+      // 8 bits => 1 byte
+      // 9 bits => 2 bytes
+      const bytesNeeded = ((bitsNeeded - 1) >> 3) + 1; // `ceil(bitsNeeded / 8)` (NB: `x >> 3` is `floor(x / 8)`)
+      const buf = this.readBytes(bytesNeeded);
+      for (let i = 0; i < bytesNeeded; i++) {
+        res |= buf[i] << (i * 8);
+      }
+
+      // NB: in JavaScript, bit shift operators always shift by modulo 32 of the right-hand operand (see
+      // https://tc39.es/ecma262/multipage/ecmascript-data-types-and-values.html#sec-numeric-types-number-unsignedRightShift),
+      // so `res >>> 32` is equivalent to `res >>> 0` (but we don't want that)
+      const newBits = bitsNeeded < 32 ? res >>> bitsNeeded : 0;
+      res = res << this.bitsLeft | this.bits;
+      this.bits = newBits;
+    } else {
+      res = this.bits;
+      this.bits >>>= n;
+    }
+
+    this.bitsLeft = -bitsNeeded & 7; // `-bitsNeeded mod 8`
+
+    // always return an unsigned 32-bit integer
+    if (n < 32) {
+      const mask = (1 << n) - 1;
+      res &= mask; // this produces a signed 32-bit int, but the sign bit is cleared
+    } else {
+      res >>>= 0;
+    }
+    return res;
+  }
+
+  /**
+   * Native endianness. Either KaitaiStream.BIG_ENDIAN or KaitaiStream.LITTLE_ENDIAN
+   * depending on the platform endianness.
+   */
+  public static endianness: boolean = new Int8Array(new Int16Array([1]).buffer)[0] > 0;
+
+  // ========================================================================
+  // Byte arrays
+  // ========================================================================
+
+  /**
+   * @param len The number of bytes to read.
+   * @returns The read bytes.
+   */
+  public readBytes(len: number): Uint8Array {
+    return this.mapUint8Array(len);
+  }
+
+  /**
+   * @returns The read bytes.
+   */
+  public readBytesFull(): Uint8Array {
+    return this.mapUint8Array(this.size - this.pos);
+  }
+
+  /**
+   * Reads bytes until the terminator byte is found.
+   *
+   * @param terminator The terminator byte.
+   * @param include True if the terminator should be included with the returned bytes.
+   * @param consume True if the terminator should be consumed from the input stream.
+   * @param eosError True to throw an error if the end of stream is reached.
+   * @returns The read bytes.
+   * @throws {string}
+   */
+  public readBytesTerm(terminator: number, include: boolean, consume: boolean, eosError: boolean): Uint8Array {
+    const blen = this.size - this.pos;
+    const u8 = new Uint8Array(this._buffer, this._byteOffset + this.pos);
+    let i;
+    for (i = 0; i < blen && u8[i] !== terminator; i++); // find first zero byte
+    if (i === blen) {
+      // we've read all the buffer and haven't found the terminator
+      if (eosError) {
+        throw "End of stream reached, but no terminator " + terminator + " found";
+      } else {
+        return this.mapUint8Array(i);
+      }
+    } else {
+      let arr;
+      if (include) {
+        arr = this.mapUint8Array(i + 1);
+      } else {
+        arr = this.mapUint8Array(i);
+      }
+      if (consume) {
+        this.pos += 1;
+      }
+      return arr;
+    }
+  }
+
+  /**
+   * Reads bytes until the terminator byte sequence is found.
+   *
+   * @param terminator The terminator byte sequence.
+   * @param include True if the terminator should be included with the returned bytes.
+   * @param consume True if the terminator should be consumed from the input stream.
+   * @param eosError True to throw an error if the end of stream is reached.
+   * @returns The read bytes.
+   * @throws {string}
+   */
+  public readBytesTermMulti(terminator: Uint8Array, include: boolean, consume: boolean, eosError: boolean): Uint8Array {
+    const unitSize = terminator.length;
+    const data = new Uint8Array(this._buffer, this._byteOffset + this.pos, this.size - this.pos);
+    let res = KaitaiStream.bytesTerminateMulti(data, terminator, true);
+    this.pos += res.length;
+    const termFound =
+        res.length !== 0 &&
+        res.length % unitSize === 0 &&
+        KaitaiStream.byteArrayCompare(new Uint8Array(res.buffer, res.length - unitSize), terminator) === 0;
+    if (termFound) {
+      if (!include) {
+        res = new Uint8Array(res.buffer, res.byteOffset, res.length - unitSize);
+      }
+      if (!consume) {
+        this.pos -= unitSize;
+      }
+    } else if (eosError) {
+      throw new Error("End of stream reached, but no terminator " + terminator + " found");
+    }
+    return res;
+  }
+
+  /**
+   * Unused since Kaitai Struct Compiler v0.9+ - compatibility with older versions.
+   *
+   * @param expected The expected bytes.
+   * @returns The read bytes.
+   * @throws {KaitaiStream.UnexpectedDataError}
+   */
+  public ensureFixedContents(expected: ArrayLike<number>): Uint8Array {
+    const actual = this.readBytes(expected.length);
+    if (actual.length !== expected.length) {
+      throw new KaitaiStream.UnexpectedDataError(expected, actual);
+    }
+    const actLen = actual.length;
+    for (let i = 0; i < actLen; i++) {
+      if (actual[i] !== expected[i]) {
+        throw new KaitaiStream.UnexpectedDataError(expected, actual);
+      }
+    }
+    return actual;
+  }
+
+  /**
+   * @param data The data.
+   * @param padByte The byte to strip.
+   * @returns The stripped data.
+   */
+  public static bytesStripRight(data: Uint8Array, padByte: number): Uint8Array {
+    let newLen = data.length;
+    while (data[newLen - 1] === padByte) {
+      newLen--;
+    }
+    return data.slice(0, newLen);
+  }
+
+  /**
+   * @param data The data.
+   * @param term The terminator.
+   * @param include True if the returned bytes should include the terminator.
+   * @returns The terminated bytes.
+   */
+  public static bytesTerminate(data: Uint8Array, term: number, include: boolean): Uint8Array {
+    let newLen = 0;
+    const maxLen = data.length;
+    while (newLen < maxLen && data[newLen] !== term) {
+      newLen++;
+    }
+    if (include && newLen < maxLen)
+      newLen++;
+    return data.slice(0, newLen);
+  }
+
+  /**
+   * @param data The data.
+   * @param term The terminator.
+   * @param include True if the returned bytes should include the terminator.
+   * @returns The terminated bytes.
+   */
+  public static bytesTerminateMulti(data: Uint8Array, term: Uint8Array, include: boolean): Uint8Array {
+    const unitSize = term.length;
+    if (unitSize === 0) {
+      return new Uint8Array();
+    }
+    const len = data.length;
+    let iTerm = 0;
+    for (let iData = 0; iData < len;) {
+      if (data[iData] !== term[iTerm]) {
+        iData += unitSize - iTerm;
+        iTerm = 0;
+        continue;
+      }
+      iData++;
+      iTerm++;
+      if (iTerm === unitSize) {
+        return data.slice(0, iData - (include ? 0 : unitSize));
+      }
+    }
+    return data.slice();
+  }
+
+  /**
+   * @param arr The bytes.
+   * @param encoding The character encoding.
+   * @returns The decoded string.
+   */
+  public static bytesToStr(arr: Uint8Array, encoding: string): string {
+    if (encoding == null || encoding.toLowerCase() === "ascii") {
+      return KaitaiStream.createStringFromArray(arr);
+    } else {
+      if (typeof TextDecoder === 'function') {
+        // we're in a browser that supports TextDecoder, or in Node.js 11 or later
+        return (new TextDecoder(encoding)).decode(arr);
+      } else {
+        // probably we're in Node.js < 11
+
+        // check if it's supported natively by Node.js Buffer
+        // see https://nodejs.org/docs/latest-v10.x/api/buffer.html#buffer_buffers_and_character_encodings
+        switch (encoding.toLowerCase()) {
+          case 'utf8':
+          case 'utf-8':
+          case 'ucs2':
+          case 'ucs-2':
+          case 'utf16le':
+          case 'utf-16le':
+            return Buffer.from(arr).toString(encoding as BufferEncoding);
+          default:
+            // unsupported encoding, we'll have to resort to iconv-lite
+            if (typeof KaitaiStream.iconvlite === 'undefined')
+              KaitaiStream.iconvlite = require('iconv-lite') as IconvLite;
+
+            return KaitaiStream.iconvlite.decode(arr, encoding);
+        }
+      }
+    }
+  }
+
+  // ========================================================================
+  // Byte array processing
+  // ========================================================================
+
+  /**
+   * @param data The input bytes.
+   * @param key The key byte.
+   * @returns The Xor'd bytes.
+   */
+  public static processXorOne(data: Uint8Array, key: number): Uint8Array {
+    const r = new Uint8Array(data.length);
+    const dl = data.length;
+    for (let i = 0; i < dl; i++)
+      r[i] = data[i] ^ key;
+    return r;
+  }
+
+  /**
+   * @param data The input bytes.
+   * @param key The key bytes.
+   * @returns The Xor'd bytes.
+   */
+  public static processXorMany(data: Uint8Array, key: Uint8Array): Uint8Array {
+    const dl = data.length;
+    const r = new Uint8Array(dl);
+    const kl = key.length;
+    let ki = 0;
+    for (let i = 0; i < dl; i++) {
+      r[i] = data[i] ^ key[ki];
+      ki++;
+      if (ki >= kl)
+        ki = 0;
+    }
+    return r;
+  }
+
+  /**
+   * @param data The input bytes.
+   * @param amount The shift amount in bits.
+   * @param groupSize The number of bytes in each group.
+   * @returns The rotated bytes.
+   * @throws {string}
+   */
+  public static processRotateLeft(data: Uint8Array, amount: number, groupSize: number): Uint8Array {
+    if (groupSize !== 1)
+      throw ("unable to rotate group of " + groupSize + " bytes yet");
+
+    const mask = groupSize * 8 - 1;
+    const antiAmount = -amount & mask;
+
+    const r = new Uint8Array(data.length);
+    for (let i = 0; i < data.length; i++)
+      r[i] = (data[i] << amount) & 0xff | (data[i] >> antiAmount);
+
+    return r;
+  }
+
+  /**
+   * @param buf The input bytes.
+   * @returns The uncompressed bytes.
+   */
+  public static processZlib(buf: Uint8Array): Uint8Array {
+    if (typeof require !== 'undefined') {
+      // require is available - we're running under node
+      if (typeof KaitaiStream.zlib === 'undefined')
+        KaitaiStream.zlib = require('zlib') as Zlib;
+      // use node's zlib module API
+      const r = (KaitaiStream.zlib as Zlib).inflateSync(
+          Buffer.from(buf.buffer.slice(buf.byteOffset, buf.byteOffset + buf.byteLength))
+      );
+      return new Uint8Array(r.buffer, r.byteOffset, r.length);
+    } else {
+      // no require() - assume we're running as a web worker in browser.
+      // user should have configured KaitaiStream.depUrls.zlib, if not
+      // we'll throw.
+      if (typeof KaitaiStream.zlib === 'undefined'
+        && typeof KaitaiStream.depUrls.zlib !== 'undefined') {
+        importScripts(KaitaiStream.depUrls.zlib);
+        KaitaiStream.zlib = pako;
+      }
+      // use pako API
+      return (KaitaiStream.zlib as Pako).inflate(buf);
+    }
+  }
+
+  // ========================================================================
+  // Misc runtime operations
+  // ========================================================================
+
+  /**
+   * @param a The dividend.
+   * @param b The divisor.
+   * @returns The result of `a` mod `b`.
+   * @throws {string}
+   */
+  public static mod(a: number, b: number): number {
+    if (b <= 0)
+      throw "mod divisor <= 0";
+    let r = a % b;
+    if (r < 0)
+      r += b;
+    return r;
+  }
+
+  /**
+   * Gets the smallest value in an array.
+   *
+   * @param arr The input array.
+   * @returns The smallest value.
+   */
+  public static arrayMin(arr: ArrayLike<number>): number {
+    let min = arr[0];
+    let x;
+    for (let i = 1, n = arr.length; i < n; ++i) {
+      x = arr[i];
+      if (x < min) min = x;
+    }
+    return min;
+  }
+
+  /**
+   * Gets the largest value in an array.
+   *
+   * @param arr The input array.
+   * @returns The largest value.
+   */
+  public static arrayMax(arr: ArrayLike<number>): number {
+    let max = arr[0];
+    let x;
+    for (let i = 1, n = arr.length; i < n; ++i) {
+      x = arr[i];
+      if (x > max) max = x;
+    }
+    return max;
+  }
+
+  /**
+   * Compares two arrays of bytes from left to right.
+   *
+   * @param a The first array.
+   * @param b The second array.
+   * @returns `0` if the arrays are the equal, a positive number if `a` is greater than `b`, or a negative number if `a` is less than `b`.
+   */
+  public static byteArrayCompare(a: Uint8Array, b: Uint8Array): number {
+    if (a === b)
+      return 0;
+    const al = a.length;
+    const bl = b.length;
+    const minLen = al < bl ? al : bl;
+    for (let i = 0; i < minLen; i++) {
+      const cmp = a[i] - b[i];
+      if (cmp !== 0)
+        return cmp;
+    }
+
+    // Reached the end of at least one of the arrays
+    if (al === bl) {
+      return 0;
+    } else {
+      return al - bl;
+    }
+  }
+
+  // ========================================================================
+  // Internal implementation details
+  // ========================================================================
+
+  public static EOFError = class EOFError extends Error {
+    public name = "EOFError";
+    public bytesReq: number;
+    public bytesAvail: number;
+
+    /**
+     * @param bytesReq The number of bytes requested.
+     * @param bytesAvail The number of bytes available.
+     */
+    public constructor(bytesReq: number, bytesAvail: number) {
+      super("requested " + bytesReq + " bytes, but only " + bytesAvail + " bytes available");
+      // Workaround https://www.typescriptlang.org/docs/handbook/2/classes.html#inheriting-built-in-types
+      Object.setPrototypeOf(this, KaitaiStream.EOFError.prototype);
+      this.bytesReq = bytesReq;
+      this.bytesAvail = bytesAvail;
+    }
+  };
+
+  /**
+   * Unused since Kaitai Struct Compiler v0.9+ - compatibility with older versions.
+   */
+  public static UnexpectedDataError = class UnexpectedDataError extends Error {
+    public name = "UnexpectedDataError";
+    public expected: any;
+    public actual: any;
+
+    /**
+     * @param expected The expected value.
+     * @param actual The actual value.
+     */
+    public constructor(expected: any, actual: any) {
+      super("expected [" + expected + "], but got [" + actual + "]");
+      // Workaround https://www.typescriptlang.org/docs/handbook/2/classes.html#inheriting-built-in-types
+      Object.setPrototypeOf(this, KaitaiStream.UnexpectedDataError.prototype);
+      this.expected = expected;
+      this.actual = actual;
+    }
+  };
+
+  public static UndecidedEndiannessError = class UndecidedEndiannessError extends Error {
+    public name = "UndecidedEndiannessError";
+
+    public constructor() {
+      super();
+      // Workaround https://www.typescriptlang.org/docs/handbook/2/classes.html#inheriting-built-in-types
+      Object.setPrototypeOf(this, KaitaiStream.UndecidedEndiannessError.prototype);
+    }
+  };
+
+  public static ValidationNotEqualError = class ValidationNotEqualError extends Error {
+    public name = "ValidationNotEqualError";
+    public expected: any;
+    public actual: any;
+
+    /**
+     * @param expected The expected value.
+     * @param actual The actual value.
+     */
+    public constructor(expected: any, actual: any) {
+      super("not equal, expected [" + expected + "], but got [" + actual + "]");
+      // Workaround https://www.typescriptlang.org/docs/handbook/2/classes.html#inheriting-built-in-types
+      Object.setPrototypeOf(this, KaitaiStream.ValidationNotEqualError.prototype);
+      this.expected = expected;
+      this.actual = actual;
+    }
+  };
+
+  public static ValidationLessThanError = class ValidationLessThanError extends Error {
+    public name = "ValidationLessThanError";
+    public min: any;
+    public actual: any;
+
+    /**
+     * @param min The minimum allowed value.
+     * @param actual The actual value.
+     */
+    public constructor(min: any, actual: any) {
+      super("not in range, min [" + min + "], but got [" + actual + "]");
+      // Workaround https://www.typescriptlang.org/docs/handbook/2/classes.html#inheriting-built-in-types
+      Object.setPrototypeOf(this, KaitaiStream.ValidationLessThanError.prototype);
+      this.min = min;
+      this.actual = actual;
+    }
+  };
+
+  public static ValidationGreaterThanError = class ValidationGreaterThanError extends Error {
+    public name = "ValidationGreaterThanError";
+    public max: any;
+    public actual: any;
+
+    /**
+     * @param max The maximum allowed value.
+     * @param actual The actual value.
+     */
+    public constructor(max: any, actual: any) {
+      super("not in range, max [" + max + "], but got [" + actual + "]");
+      // Workaround https://www.typescriptlang.org/docs/handbook/2/classes.html#inheriting-built-in-types
+      Object.setPrototypeOf(this, KaitaiStream.ValidationGreaterThanError.prototype);
+      this.max = max;
+      this.actual = actual;
+    }
+  };
+
+  public static ValidationNotAnyOfError = class ValidationNotAnyOfError extends Error {
+    public name = "ValidationNotAnyOfError";
+    public actual: any;
+
+    /**
+     * @param actual The actual value.
+     */
+    public constructor(actual: any) {
+      super("not any of the list, got [" + actual + "]");
+      // Workaround https://www.typescriptlang.org/docs/handbook/2/classes.html#inheriting-built-in-types
+      Object.setPrototypeOf(this, KaitaiStream.ValidationNotAnyOfError.prototype);
+      this.actual = actual;
+    }
+  };
+
+  public static ValidationNotInEnumError = class ValidationNotInEnumError extends Error {
+    public name = "ValidationNotInEnumError";
+    public actual: any;
+
+    /**
+     * @param actual The actual value.
+     */
+    public constructor(actual: any) {
+      super("not in the enum, got [" + actual + "]");
+      // Workaround https://www.typescriptlang.org/docs/handbook/2/classes.html#inheriting-built-in-types
+      Object.setPrototypeOf(this, KaitaiStream.ValidationNotInEnumError.prototype);
+      this.actual = actual;
+    }
+  };
+
+  public static ValidationExprError = class ValidationExprError extends Error {
+    public name = "ValidationExprError";
+    public actual: any;
+
+    /**
+     * @param actual The actual value.
+     */
+    public constructor(actual: any) {
+      super("not matching the expression, got [" + actual + "]");
+      // Workaround https://www.typescriptlang.org/docs/handbook/2/classes.html#inheriting-built-in-types
+      Object.setPrototypeOf(this, KaitaiStream.ValidationExprError.prototype);
+      this.actual = actual;
+    }
+  };
+
+  /**
+   * Ensures that we have at least `length` bytes left in the stream.
+   * If not, throws an EOFError.
+   *
+   * @param length Number of bytes to require.
+   * @throws {KaitaiStream.EOFError}
+   */
+  public ensureBytesLeft(length: number): void {
+    if (this.pos + length > this.size) {
+      throw new KaitaiStream.EOFError(length, this.size - this.pos);
+    }
+  }
+
+  /**
+   * Maps a Uint8Array into the KaitaiStream buffer.
+   * Nice for quickly reading in data.
+   *
+   * @param length Number of elements to map.
+   * @returns A Uint8Array to the KaitaiStream backing buffer.
+   */
+  public mapUint8Array(length: number): Uint8Array {
+    length |= 0;
+
+    this.ensureBytesLeft(length);
+
+    const arr = new Uint8Array(this._buffer, this.byteOffset + this.pos, length);
+    this.pos += length;
+    return arr;
+  }
+
+  /**
+   * Creates an array from an array of character codes.
+   * Uses String.fromCharCode in chunks for memory efficiency and then concatenates
+   * the resulting string chunks.
+   *
+   * @param array Array of character codes.
+   * @returns String created from the character codes.
+   */
+  public static createStringFromArray(array: Uint8Array): string {
+    const chunk_size = 0x8000;
+    const chunks = [];
+    for (let i = 0; i < array.length; i += chunk_size) {
+      const chunk = array.subarray(i, i + chunk_size);
+      chunks.push(String.fromCharCode.apply(null, chunk));
+    }
+    return chunks.join("");
+  }
+}
+
+export default KaitaiStream;
diff --git a/README.md b/README.md
index d3a2afe..0141140 100644
--- a/README.md
+++ b/README.md
@@ -16,6 +16,20 @@ Further reading:
 * [About API implemented in this library](http://doc.kaitai.io/stream_api.html)
 * [JavaScript-specific notes](http://doc.kaitai.io/lang_javascript.html) - also includes Quick start guide
 
+## Development
+
+After cloning this repository, you must run these commands to compile the
+TypeScript source file [`KaitaiStream.ts`](./KaitaiStream.ts) into the
+`KaitaiStream.js` file (ignored by Git) with JavaScript code:
+
+```shell
+npm install
+npm run build
+```
+
+`npm run build` also needs to be run after each change to
+[`KaitaiStream.ts`](./KaitaiStream.ts).
+
 ## Licensing
 
 Copyright 2012-2016 Ilmari Heikkinen\
diff --git a/index.d.ts b/index.d.ts
new file mode 100644
index 0000000..a31ec9a
--- /dev/null
+++ b/index.d.ts
@@ -0,0 +1,5 @@
+import KaitaiStream = require("./KaitaiStream");
+declare const _default: {
+    KaitaiStream: typeof KaitaiStream;
+};
+export = _default;
diff --git a/package-lock.json b/package-lock.json
index 87761dd..b02e9bc 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -7,7 +7,219 @@
     "": {
       "name": "kaitai-struct",
       "version": "0.11.0-SNAPSHOT.1",
-      "license": "Apache-2.0"
+      "license": "Apache-2.0",
+      "devDependencies": {
+        "@rollup/plugin-typescript": "^8.3.0",
+        "@types/node": "^16.11.11",
+        "rollup": "^2.60.2",
+        "tslib": "^2.3.1",
+        "typescript": "^4.5.2"
+      }
+    },
+    "node_modules/@rollup/plugin-typescript": {
+      "version": "8.5.0",
+      "resolved": "https://registry.npmjs.org/@rollup/plugin-typescript/-/plugin-typescript-8.5.0.tgz",
+      "integrity": "sha512-wMv1/scv0m/rXx21wD2IsBbJFba8wGF3ErJIr6IKRfRj49S85Lszbxb4DCo8iILpluTjk2GAAu9CoZt4G3ppgQ==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@rollup/pluginutils": "^3.1.0",
+        "resolve": "^1.17.0"
+      },
+      "engines": {
+        "node": ">=8.0.0"
+      },
+      "peerDependencies": {
+        "rollup": "^2.14.0",
+        "tslib": "*",
+        "typescript": ">=3.7.0"
+      },
+      "peerDependenciesMeta": {
+        "tslib": {
+          "optional": true
+        }
+      }
+    },
+    "node_modules/@rollup/pluginutils": {
+      "version": "3.1.0",
+      "resolved": "https://registry.npmjs.org/@rollup/pluginutils/-/pluginutils-3.1.0.tgz",
+      "integrity": "sha512-GksZ6pr6TpIjHm8h9lSQ8pi8BE9VeubNT0OMJ3B5uZJ8pz73NPiqOtCog/x2/QzM1ENChPKxMDhiQuRHsqc+lg==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@types/estree": "0.0.39",
+        "estree-walker": "^1.0.1",
+        "picomatch": "^2.2.2"
+      },
+      "engines": {
+        "node": ">= 8.0.0"
+      },
+      "peerDependencies": {
+        "rollup": "^1.20.0||^2.0.0"
+      }
+    },
+    "node_modules/@types/estree": {
+      "version": "0.0.39",
+      "resolved": "https://registry.npmjs.org/@types/estree/-/estree-0.0.39.tgz",
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+      "dev": true,
+      "license": "MIT"
+    },
+    "node_modules/@types/node": {
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+      "resolved": "https://registry.npmjs.org/@types/node/-/node-16.18.112.tgz",
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+      "dev": true,
+      "license": "MIT"
+    },
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+      "resolved": "https://registry.npmjs.org/estree-walker/-/estree-walker-1.0.1.tgz",
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+      "dev": true,
+      "license": "MIT"
+    },
+    "node_modules/fsevents": {
+      "version": "2.3.3",
+      "resolved": "https://registry.npmjs.org/fsevents/-/fsevents-2.3.3.tgz",
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+      "dev": true,
+      "hasInstallScript": true,
+      "license": "MIT",
+      "optional": true,
+      "os": [
+        "darwin"
+      ],
+      "engines": {
+        "node": "^8.16.0 || ^10.6.0 || >=11.0.0"
+      }
+    },
+    "node_modules/function-bind": {
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+      "dev": true,
+      "license": "MIT",
+      "funding": {
+        "url": "https://github.com/sponsors/ljharb"
+      }
+    },
+    "node_modules/hasown": {
+      "version": "2.0.2",
+      "resolved": "https://registry.npmjs.org/hasown/-/hasown-2.0.2.tgz",
+      "integrity": "sha512-0hJU9SCPvmMzIBdZFqNPXWa6dqh7WdH0cII9y+CyS8rG3nL48Bclra9HmKhVVUHyPWNH5Y7xDwAB7bfgSjkUMQ==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "function-bind": "^1.1.2"
+      },
+      "engines": {
+        "node": ">= 0.4"
+      }
+    },
+    "node_modules/is-core-module": {
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+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "hasown": "^2.0.2"
+      },
+      "engines": {
+        "node": ">= 0.4"
+      },
+      "funding": {
+        "url": "https://github.com/sponsors/ljharb"
+      }
+    },
+    "node_modules/path-parse": {
+      "version": "1.0.7",
+      "resolved": "https://registry.npmjs.org/path-parse/-/path-parse-1.0.7.tgz",
+      "integrity": "sha512-LDJzPVEEEPR+y48z93A0Ed0yXb8pAByGWo/k5YYdYgpY2/2EsOsksJrq7lOHxryrVOn1ejG6oAp8ahvOIQD8sw==",
+      "dev": true,
+      "license": "MIT"
+    },
+    "node_modules/picomatch": {
+      "version": "2.3.1",
+      "resolved": "https://registry.npmjs.org/picomatch/-/picomatch-2.3.1.tgz",
+      "integrity": "sha512-JU3teHTNjmE2VCGFzuY8EXzCDVwEqB2a8fsIvwaStHhAWJEeVd1o1QD80CU6+ZdEXXSLbSsuLwJjkCBWqRQUVA==",
+      "dev": true,
+      "license": "MIT",
+      "engines": {
+        "node": ">=8.6"
+      },
+      "funding": {
+        "url": "https://github.com/sponsors/jonschlinkert"
+      }
+    },
+    "node_modules/resolve": {
+      "version": "1.22.8",
+      "resolved": "https://registry.npmjs.org/resolve/-/resolve-1.22.8.tgz",
+      "integrity": "sha512-oKWePCxqpd6FlLvGV1VU0x7bkPmmCNolxzjMf4NczoDnQcIWrAF+cPtZn5i6n+RfD2d9i0tzpKnG6Yk168yIyw==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "is-core-module": "^2.13.0",
+        "path-parse": "^1.0.7",
+        "supports-preserve-symlinks-flag": "^1.0.0"
+      },
+      "bin": {
+        "resolve": "bin/resolve"
+      },
+      "funding": {
+        "url": "https://github.com/sponsors/ljharb"
+      }
+    },
+    "node_modules/rollup": {
+      "version": "2.79.2",
+      "resolved": "https://registry.npmjs.org/rollup/-/rollup-2.79.2.tgz",
+      "integrity": "sha512-fS6iqSPZDs3dr/y7Od6y5nha8dW1YnbgtsyotCVvoFGKbERG++CVRFv1meyGDE1SNItQA8BrnCw7ScdAhRJ3XQ==",
+      "dev": true,
+      "license": "MIT",
+      "bin": {
+        "rollup": "dist/bin/rollup"
+      },
+      "engines": {
+        "node": ">=10.0.0"
+      },
+      "optionalDependencies": {
+        "fsevents": "~2.3.2"
+      }
+    },
+    "node_modules/supports-preserve-symlinks-flag": {
+      "version": "1.0.0",
+      "resolved": "https://registry.npmjs.org/supports-preserve-symlinks-flag/-/supports-preserve-symlinks-flag-1.0.0.tgz",
+      "integrity": "sha512-ot0WnXS9fgdkgIcePe6RHNk1WA8+muPa6cSjeR3V8K27q9BB1rTE3R1p7Hv0z1ZyAc8s6Vvv8DIyWf681MAt0w==",
+      "dev": true,
+      "license": "MIT",
+      "engines": {
+        "node": ">= 0.4"
+      },
+      "funding": {
+        "url": "https://github.com/sponsors/ljharb"
+      }
+    },
+    "node_modules/tslib": {
+      "version": "2.7.0",
+      "resolved": "https://registry.npmjs.org/tslib/-/tslib-2.7.0.tgz",
+      "integrity": "sha512-gLXCKdN1/j47AiHiOkJN69hJmcbGTHI0ImLmbYLHykhgeN0jVGola9yVjFgzCUklsZQMW55o+dW7IXv3RCXDzA==",
+      "dev": true,
+      "license": "0BSD"
+    },
+    "node_modules/typescript": {
+      "version": "4.9.5",
+      "resolved": "https://registry.npmjs.org/typescript/-/typescript-4.9.5.tgz",
+      "integrity": "sha512-1FXk9E2Hm+QzZQ7z+McJiHL4NW1F2EzMu9Nq9i3zAaGqibafqYwCVU6WyWAuyQRRzOlxou8xZSyXLEN8oKj24g==",
+      "dev": true,
+      "license": "Apache-2.0",
+      "bin": {
+        "tsc": "bin/tsc",
+        "tsserver": "bin/tsserver"
+      },
+      "engines": {
+        "node": ">=4.2.0"
+      }
     }
   }
 }
diff --git a/package.json b/package.json
index d57d4a7..c125fce 100644
--- a/package.json
+++ b/package.json
@@ -2,20 +2,6 @@
   "name": "kaitai-struct",
   "version": "0.11.0-SNAPSHOT.1",
   "description": "Kaitai Struct: runtime library for JavaScript",
-  "license": "Apache-2.0",
-  "author": "Kaitai team (https://github.com/orgs/kaitai-io/people) and Ilmari Heikkinen",
-  "homepage": "https://github.com/kaitai-io/kaitai_struct_javascript_runtime#readme",
-  "repository": {
-    "type": "git",
-    "url": "https://github.com/kaitai-io/kaitai_struct_javascript_runtime.git"
-  },
-  "bugs": {
-    "url": "https://github.com/kaitai-io/kaitai_struct_javascript_runtime/issues"
-  },
-  "main": "index.js",
-  "files": [
-    "KaitaiStream.js"
-  ],
   "keywords": [
     "binary",
     "file",
@@ -29,5 +15,32 @@
     "stream",
     "struct",
     "structure"
-  ]
+  ],
+  "homepage": "https://github.com/kaitai-io/kaitai_struct_javascript_runtime#readme",
+  "bugs": {
+    "url": "https://github.com/kaitai-io/kaitai_struct_javascript_runtime/issues"
+  },
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/kaitai-io/kaitai_struct_javascript_runtime.git"
+  },
+  "license": "Apache-2.0",
+  "author": "Kaitai team (https://github.com/orgs/kaitai-io/people) and Ilmari Heikkinen",
+  "main": "index.js",
+  "types": "index.d.ts",
+  "files": [
+    "KaitaiStream.js",
+    "KaitaiStream.d.ts",
+    "index.d.ts"
+  ],
+  "scripts": {
+    "build": "rollup -c"
+  },
+  "devDependencies": {
+    "@rollup/plugin-typescript": "^8.3.0",
+    "@types/node": "^16.11.11",
+    "rollup": "^2.60.2",
+    "tslib": "^2.3.1",
+    "typescript": "^4.5.2"
+  }
 }
diff --git a/rollup.config.js b/rollup.config.js
new file mode 100644
index 0000000..b6ad679
--- /dev/null
+++ b/rollup.config.js
@@ -0,0 +1,11 @@
+import typescript from '@rollup/plugin-typescript';
+
+export default [{
+    input: 'KaitaiStream.ts',
+    output: {
+        dir: '.',
+        format: 'umd',
+        name: 'KaitaiStream'
+    },
+    plugins: [typescript()]
+}];
diff --git a/tsconfig.json b/tsconfig.json
new file mode 100644
index 0000000..86e0333
--- /dev/null
+++ b/tsconfig.json
@@ -0,0 +1,102 @@
+{
+  "compilerOptions": {
+    /* Visit https://aka.ms/tsconfig.json to read more about this file */
+
+    /* Projects */
+    // "incremental": true,                              /* Enable incremental compilation */
+    // "composite": true,                                /* Enable constraints that allow a TypeScript project to be used with project references. */
+    // "tsBuildInfoFile": "./",                          /* Specify the folder for .tsbuildinfo incremental compilation files. */
+    // "disableSourceOfProjectReferenceRedirect": true,  /* Disable preferring source files instead of declaration files when referencing composite projects */
+    // "disableSolutionSearching": true,                 /* Opt a project out of multi-project reference checking when editing. */
+    // "disableReferencedProjectLoad": true,             /* Reduce the number of projects loaded automatically by TypeScript. */
+
+    /* Language and Environment */
+    "target": "es5",                                     /* Set the JavaScript language version for emitted JavaScript and include compatible library declarations. */
+    // "lib": [],                                        /* Specify a set of bundled library declaration files that describe the target runtime environment. */
+    // "jsx": "preserve",                                /* Specify what JSX code is generated. */
+    // "experimentalDecorators": true,                   /* Enable experimental support for TC39 stage 2 draft decorators. */
+    // "emitDecoratorMetadata": true,                    /* Emit design-type metadata for decorated declarations in source files. */
+    // "jsxFactory": "",                                 /* Specify the JSX factory function used when targeting React JSX emit, e.g. 'React.createElement' or 'h' */
+    // "jsxFragmentFactory": "",                         /* Specify the JSX Fragment reference used for fragments when targeting React JSX emit e.g. 'React.Fragment' or 'Fragment'. */
+    // "jsxImportSource": "",                            /* Specify module specifier used to import the JSX factory functions when using `jsx: react-jsx*`.` */
+    // "reactNamespace": "",                             /* Specify the object invoked for `createElement`. This only applies when targeting `react` JSX emit. */
+    // "noLib": true,                                    /* Disable including any library files, including the default lib.d.ts. */
+    // "useDefineForClassFields": true,                  /* Emit ECMAScript-standard-compliant class fields. */
+
+    /* Modules */
+    "module": "es2015",                                  /* Specify what module code is generated. */
+    // "rootDir": "./",                                  /* Specify the root folder within your source files. */
+    // "moduleResolution": "node",                       /* Specify how TypeScript looks up a file from a given module specifier. */
+    // "baseUrl": "./",                                  /* Specify the base directory to resolve non-relative module names. */
+    // "paths": {},                                      /* Specify a set of entries that re-map imports to additional lookup locations. */
+    // "rootDirs": [],                                   /* Allow multiple folders to be treated as one when resolving modules. */
+    // "typeRoots": [],                                  /* Specify multiple folders that act like `./node_modules/@types`. */
+    // "types": [],                                      /* Specify type package names to be included without being referenced in a source file. */
+    // "allowUmdGlobalAccess": true,                     /* Allow accessing UMD globals from modules. */
+    // "resolveJsonModule": true,                        /* Enable importing .json files */
+    // "noResolve": true,                                /* Disallow `import`s, `require`s or `<reference>`s from expanding the number of files TypeScript should add to a project. */
+
+    /* JavaScript Support */
+    // "allowJs": true,                                  /* Allow JavaScript files to be a part of your program. Use the `checkJS` option to get errors from these files. */
+    // "checkJs": true,                                  /* Enable error reporting in type-checked JavaScript files. */
+    // "maxNodeModuleJsDepth": 1,                        /* Specify the maximum folder depth used for checking JavaScript files from `node_modules`. Only applicable with `allowJs`. */
+
+    /* Emit */
+    "declaration": true,                                 /* Generate .d.ts files from TypeScript and JavaScript files in your project. */
+    // "declarationMap": true,                           /* Create sourcemaps for d.ts files. */
+    // "emitDeclarationOnly": true,                      /* Only output d.ts files and not JavaScript files. */
+    // "sourceMap": true,                                /* Create source map files for emitted JavaScript files. */
+    // "outFile": "./",                                  /* Specify a file that bundles all outputs into one JavaScript file. If `declaration` is true, also designates a file that bundles all .d.ts output. */
+    "outDir": "./",                                      /* Specify an output folder for all emitted files. */
+    // "removeComments": true,                           /* Disable emitting comments. */
+    // "noEmit": true,                                   /* Disable emitting files from a compilation. */
+    // "importHelpers": true,                            /* Allow importing helper functions from tslib once per project, instead of including them per-file. */
+    // "importsNotUsedAsValues": "remove",               /* Specify emit/checking behavior for imports that are only used for types */
+    // "downlevelIteration": true,                       /* Emit more compliant, but verbose and less performant JavaScript for iteration. */
+    // "sourceRoot": "",                                 /* Specify the root path for debuggers to find the reference source code. */
+    // "mapRoot": "",                                    /* Specify the location where debugger should locate map files instead of generated locations. */
+    // "inlineSourceMap": true,                          /* Include sourcemap files inside the emitted JavaScript. */
+    // "inlineSources": true,                            /* Include source code in the sourcemaps inside the emitted JavaScript. */
+    // "emitBOM": true,                                  /* Emit a UTF-8 Byte Order Mark (BOM) in the beginning of output files. */
+    // "newLine": "crlf",                                /* Set the newline character for emitting files. */
+    // "stripInternal": true,                            /* Disable emitting declarations that have `@internal` in their JSDoc comments. */
+    // "noEmitHelpers": true,                            /* Disable generating custom helper functions like `__extends` in compiled output. */
+    // "noEmitOnError": true,                            /* Disable emitting files if any type checking errors are reported. */
+    // "preserveConstEnums": true,                       /* Disable erasing `const enum` declarations in generated code. */
+    // "declarationDir": "./",                           /* Specify the output directory for generated declaration files. */
+    // "preserveValueImports": true,                     /* Preserve unused imported values in the JavaScript output that would otherwise be removed. */
+
+    /* Interop Constraints */
+    // "isolatedModules": true,                          /* Ensure that each file can be safely transpiled without relying on other imports. */
+    // "allowSyntheticDefaultImports": true,             /* Allow 'import x from y' when a module doesn't have a default export. */
+    "esModuleInterop": true,                             /* Emit additional JavaScript to ease support for importing CommonJS modules. This enables `allowSyntheticDefaultImports` for type compatibility. */
+    // "preserveSymlinks": true,                         /* Disable resolving symlinks to their realpath. This correlates to the same flag in node. */
+    "forceConsistentCasingInFileNames": true,            /* Ensure that casing is correct in imports. */
+
+    /* Type Checking */
+    "strict": true,                                      /* Enable all strict type-checking options. */
+    // "noImplicitAny": true,                            /* Enable error reporting for expressions and declarations with an implied `any` type.. */
+    // "strictNullChecks": true,                         /* When type checking, take into account `null` and `undefined`. */
+    // "strictFunctionTypes": true,                      /* When assigning functions, check to ensure parameters and the return values are subtype-compatible. */
+    // "strictBindCallApply": true,                      /* Check that the arguments for `bind`, `call`, and `apply` methods match the original function. */
+    // "strictPropertyInitialization": true,             /* Check for class properties that are declared but not set in the constructor. */
+    // "noImplicitThis": true,                           /* Enable error reporting when `this` is given the type `any`. */
+    // "useUnknownInCatchVariables": true,               /* Type catch clause variables as 'unknown' instead of 'any'. */
+    // "alwaysStrict": true,                             /* Ensure 'use strict' is always emitted. */
+    // "noUnusedLocals": true,                           /* Enable error reporting when a local variables aren't read. */
+    // "noUnusedParameters": true,                       /* Raise an error when a function parameter isn't read */
+    // "exactOptionalPropertyTypes": true,               /* Interpret optional property types as written, rather than adding 'undefined'. */
+    // "noImplicitReturns": true,                        /* Enable error reporting for codepaths that do not explicitly return in a function. */
+    // "noFallthroughCasesInSwitch": true,               /* Enable error reporting for fallthrough cases in switch statements. */
+    // "noUncheckedIndexedAccess": true,                 /* Include 'undefined' in index signature results */
+    // "noImplicitOverride": true,                       /* Ensure overriding members in derived classes are marked with an override modifier. */
+    // "noPropertyAccessFromIndexSignature": true,       /* Enforces using indexed accessors for keys declared using an indexed type */
+    // "allowUnusedLabels": true,                        /* Disable error reporting for unused labels. */
+    // "allowUnreachableCode": true,                     /* Disable error reporting for unreachable code. */
+
+    /* Completeness */
+    // "skipDefaultLibCheck": true,                      /* Skip type checking .d.ts files that are included with TypeScript. */
+    "skipLibCheck": true                                 /* Skip type checking all .d.ts files. */
+  },
+  "exclude": []
+}