diff --git a/src/compiler/program.ts b/src/compiler/program.ts
index c29876ce619f5..0b577f586e8a8 100644
--- a/src/compiler/program.ts
+++ b/src/compiler/program.ts
@@ -818,6 +818,25 @@ namespace ts {
         }
     }
 
+    /** @internal */
+    export const plainJSErrors: Set<number> = new Set([
+        Diagnostics.Cannot_redeclare_block_scoped_variable_0.code,
+        Diagnostics.A_module_cannot_have_multiple_default_exports.code,
+        Diagnostics.Another_export_default_is_here.code,
+        Diagnostics.The_first_export_default_is_here.code,
+        Diagnostics.Identifier_expected_0_is_a_reserved_word_at_the_top_level_of_a_module.code,
+        Diagnostics.Identifier_expected_0_is_a_reserved_word_in_strict_mode_Modules_are_automatically_in_strict_mode.code,
+        Diagnostics.Identifier_expected_0_is_a_reserved_word_that_cannot_be_used_here.code,
+        Diagnostics.constructor_is_a_reserved_word.code,
+        Diagnostics.delete_cannot_be_called_on_an_identifier_in_strict_mode.code,
+        Diagnostics.Code_contained_in_a_class_is_evaluated_in_JavaScript_s_strict_mode_which_does_not_allow_this_use_of_0_For_more_information_see_https_Colon_Slash_Slashdeveloper_mozilla_org_Slashen_US_Slashdocs_SlashWeb_SlashJavaScript_SlashReference_SlashStrict_mode.code,
+        Diagnostics.Invalid_use_of_0_Modules_are_automatically_in_strict_mode.code,
+        Diagnostics.Invalid_use_of_0_in_strict_mode.code,
+        Diagnostics.A_label_is_not_allowed_here.code,
+        Diagnostics.Octal_literals_are_not_allowed_in_strict_mode.code,
+        Diagnostics.with_statements_are_not_allowed_in_strict_mode.code,
+    ]);
+
     /**
      * Determine if source file needs to be re-created even if its text hasn't changed
      */
@@ -2004,15 +2023,24 @@ namespace ts {
 
                 Debug.assert(!!sourceFile.bindDiagnostics);
 
-                const isCheckJs = isCheckJsEnabledForFile(sourceFile, options);
+                const isJs = sourceFile.scriptKind === ScriptKind.JS || sourceFile.scriptKind === ScriptKind.JSX;
+                const isCheckJs = isJs && isCheckJsEnabledForFile(sourceFile, options);
+                const isPlainJs = isJs && !sourceFile.checkJsDirective && options.checkJs === undefined;
                 const isTsNoCheck = !!sourceFile.checkJsDirective && sourceFile.checkJsDirective.enabled === false;
-                // By default, only type-check .ts, .tsx, 'Deferred' and 'External' files (external files are added by plugins)
-                const includeBindAndCheckDiagnostics = !isTsNoCheck && (sourceFile.scriptKind === ScriptKind.TS || sourceFile.scriptKind === ScriptKind.TSX
-                    || sourceFile.scriptKind === ScriptKind.External || isCheckJs || sourceFile.scriptKind === ScriptKind.Deferred);
-                const bindDiagnostics: readonly Diagnostic[] = includeBindAndCheckDiagnostics ? sourceFile.bindDiagnostics : emptyArray;
-                const checkDiagnostics = includeBindAndCheckDiagnostics ? typeChecker.getDiagnostics(sourceFile, cancellationToken) : emptyArray;
 
-                return getMergedBindAndCheckDiagnostics(sourceFile, includeBindAndCheckDiagnostics, bindDiagnostics, checkDiagnostics, isCheckJs ? sourceFile.jsDocDiagnostics : undefined);
+                // By default, only type-check .ts, .tsx, Deferred, plain JS, checked JS and External
+                // - plain JS: .js files with no // ts-check and checkJs: undefined
+                // - check JS: .js files with either // ts-check or checkJs: true
+                // - external: files that are added by plugins
+                const includeBindAndCheckDiagnostics = !isTsNoCheck && (sourceFile.scriptKind === ScriptKind.TS || sourceFile.scriptKind === ScriptKind.TSX
+                        || sourceFile.scriptKind === ScriptKind.External || isPlainJs || isCheckJs || sourceFile.scriptKind === ScriptKind.Deferred);
+                let bindDiagnostics: readonly Diagnostic[] = includeBindAndCheckDiagnostics ? sourceFile.bindDiagnostics : emptyArray;
+                const checkDiagnostics = includeBindAndCheckDiagnostics && !isPlainJs ? typeChecker.getDiagnostics(sourceFile, cancellationToken) : emptyArray;
+                if (isPlainJs) {
+                    bindDiagnostics = filter(bindDiagnostics, d => plainJSErrors.has(d.code));
+                }
+                // skip ts-expect-error errors in plain JS files, and skip JSDoc errors except in checked JS
+                return getMergedBindAndCheckDiagnostics(sourceFile, includeBindAndCheckDiagnostics && !isPlainJs, bindDiagnostics, checkDiagnostics, isCheckJs ? sourceFile.jsDocDiagnostics : undefined);
             });
         }
 
diff --git a/tests/baselines/reference/argumentsReferenceInConstructor4_Js.errors.txt b/tests/baselines/reference/argumentsReferenceInConstructor4_Js.errors.txt
new file mode 100644
index 0000000000000..30d6092c3f9a4
--- /dev/null
+++ b/tests/baselines/reference/argumentsReferenceInConstructor4_Js.errors.txt
@@ -0,0 +1,46 @@
+/a.js(18,9): error TS1210: Code contained in a class is evaluated in JavaScript's strict mode which does not allow this use of 'arguments'. For more information, see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Strict_mode.
+
+
+==== /a.js (1 errors) ====
+    class A {
+    	/**
+    	 * Constructor
+    	 *
+    	 * @param {object} [foo={}]
+    	 */
+    	constructor(foo = {}) {
+    		const key = "bar";
+    
+    		/**
+    		 * @type object
+    		 */
+    		this.foo = foo;
+    
+    		/**
+    		 * @type object
+    		 */
+    		const arguments = this.arguments;
+    		      ~~~~~~~~~
+!!! error TS1210: Code contained in a class is evaluated in JavaScript's strict mode which does not allow this use of 'arguments'. For more information, see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Strict_mode.
+    
+    		/**
+    		 * @type object
+    		 */
+    		this.bar = arguments.bar;
+    
+    		/**
+    		 * @type object
+    		 */
+    		this.baz = arguments[key];
+    
+    		/**
+    		 * @type object
+    		 */
+    		this.options = arguments;
+    	}
+    
+    	get arguments() {
+    		return { bar: {} };
+    	}
+    }
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/argumentsReferenceInMethod4_Js.errors.txt b/tests/baselines/reference/argumentsReferenceInMethod4_Js.errors.txt
new file mode 100644
index 0000000000000..8c90a67da1700
--- /dev/null
+++ b/tests/baselines/reference/argumentsReferenceInMethod4_Js.errors.txt
@@ -0,0 +1,44 @@
+/a.js(16,9): error TS1210: Code contained in a class is evaluated in JavaScript's strict mode which does not allow this use of 'arguments'. For more information, see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Strict_mode.
+
+
+==== /a.js (1 errors) ====
+    class A {
+    	/**
+    	 * @param {object} [foo={}]
+    	 */
+    	m(foo = {}) {
+    		const key = "bar";
+    
+    		/**
+    		 * @type object
+    		 */
+    		this.foo = foo;
+    
+    		/**
+    		 * @type object
+    		 */
+    		const arguments = this.arguments;
+    		      ~~~~~~~~~
+!!! error TS1210: Code contained in a class is evaluated in JavaScript's strict mode which does not allow this use of 'arguments'. For more information, see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Strict_mode.
+    
+    		/**
+    		 * @type object
+    		 */
+    		this.bar = arguments.bar;
+    
+    		/**
+    		 * @type object
+    		 */
+    		this.baz = arguments[key];
+    
+    		/**
+    		 * @type object
+    		 */
+    		this.options = arguments;
+    	}
+    
+    	get arguments() {
+    		return { bar: {} };
+    	}
+    }
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/jsdocTypedefNoCrash2.errors.txt b/tests/baselines/reference/jsdocTypedefNoCrash2.errors.txt
index 9448bf84a2a32..4545e41dc4991 100644
--- a/tests/baselines/reference/jsdocTypedefNoCrash2.errors.txt
+++ b/tests/baselines/reference/jsdocTypedefNoCrash2.errors.txt
@@ -1,12 +1,18 @@
+tests/cases/compiler/export.js(1,13): error TS2451: Cannot redeclare block-scoped variable 'foo'.
 tests/cases/compiler/export.js(1,13): error TS8008: Type aliases can only be used in TypeScript files.
+tests/cases/compiler/export.js(6,14): error TS2451: Cannot redeclare block-scoped variable 'foo'.
 
 
-==== tests/cases/compiler/export.js (1 errors) ====
+==== tests/cases/compiler/export.js (3 errors) ====
     export type foo = 5;
                 ~~~
+!!! error TS2451: Cannot redeclare block-scoped variable 'foo'.
+                ~~~
 !!! error TS8008: Type aliases can only be used in TypeScript files.
     /**
      * @typedef {{
      * }}
      */
-    export const foo = 5;
\ No newline at end of file
+    export const foo = 5;
+                 ~~~
+!!! error TS2451: Cannot redeclare block-scoped variable 'foo'.
\ No newline at end of file
diff --git a/tests/baselines/reference/plainJSBinderErrors.errors.txt b/tests/baselines/reference/plainJSBinderErrors.errors.txt
new file mode 100644
index 0000000000000..72aaa17b1e892
--- /dev/null
+++ b/tests/baselines/reference/plainJSBinderErrors.errors.txt
@@ -0,0 +1,97 @@
+tests/cases/conformance/salsa/plainJSBinderErrors.js(1,1): error TS2528: A module cannot have multiple default exports.
+tests/cases/conformance/salsa/plainJSBinderErrors.js(2,1): error TS2528: A module cannot have multiple default exports.
+tests/cases/conformance/salsa/plainJSBinderErrors.js(3,7): error TS1262: Identifier expected. 'await' is a reserved word at the top-level of a module.
+tests/cases/conformance/salsa/plainJSBinderErrors.js(4,7): error TS1214: Identifier expected. 'yield' is a reserved word in strict mode. Modules are automatically in strict mode.
+tests/cases/conformance/salsa/plainJSBinderErrors.js(6,11): error TS1359: Identifier expected. 'await' is a reserved word that cannot be used here.
+tests/cases/conformance/salsa/plainJSBinderErrors.js(9,11): error TS1214: Identifier expected. 'yield' is a reserved word in strict mode. Modules are automatically in strict mode.
+tests/cases/conformance/salsa/plainJSBinderErrors.js(12,5): error TS18012: '#constructor' is a reserved word.
+tests/cases/conformance/salsa/plainJSBinderErrors.js(15,20): error TS1102: 'delete' cannot be called on an identifier in strict mode.
+tests/cases/conformance/salsa/plainJSBinderErrors.js(18,16): error TS1102: 'delete' cannot be called on an identifier in strict mode.
+tests/cases/conformance/salsa/plainJSBinderErrors.js(19,16): error TS1102: 'delete' cannot be called on an identifier in strict mode.
+tests/cases/conformance/salsa/plainJSBinderErrors.js(22,15): error TS1210: Code contained in a class is evaluated in JavaScript's strict mode which does not allow this use of 'eval'. For more information, see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Strict_mode.
+tests/cases/conformance/salsa/plainJSBinderErrors.js(23,15): error TS1210: Code contained in a class is evaluated in JavaScript's strict mode which does not allow this use of 'arguments'. For more information, see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Strict_mode.
+tests/cases/conformance/salsa/plainJSBinderErrors.js(26,27): error TS1121: Octal literals are not allowed in strict mode.
+tests/cases/conformance/salsa/plainJSBinderErrors.js(27,9): error TS1101: 'with' statements are not allowed in strict mode.
+tests/cases/conformance/salsa/plainJSBinderErrors.js(33,13): error TS1344: 'A label is not allowed here.
+tests/cases/conformance/salsa/plainJSBinderErrors.js(39,7): error TS1215: Invalid use of 'eval'. Modules are automatically in strict mode.
+tests/cases/conformance/salsa/plainJSBinderErrors.js(40,7): error TS1215: Invalid use of 'arguments'. Modules are automatically in strict mode.
+
+
+==== tests/cases/conformance/salsa/plainJSBinderErrors.js (17 errors) ====
+    export default 12
+    ~~~~~~~~~~~~~~~~~
+!!! error TS2528: A module cannot have multiple default exports.
+!!! related TS2753 tests/cases/conformance/salsa/plainJSBinderErrors.js:2:1: Another export default is here.
+    export default 13
+    ~~~~~~~~~~~~~~~~~
+!!! error TS2528: A module cannot have multiple default exports.
+!!! related TS2752 tests/cases/conformance/salsa/plainJSBinderErrors.js:1:1: The first export default is here.
+    const await = 1
+          ~~~~~
+!!! error TS1262: Identifier expected. 'await' is a reserved word at the top-level of a module.
+    const yield = 2
+          ~~~~~
+!!! error TS1214: Identifier expected. 'yield' is a reserved word in strict mode. Modules are automatically in strict mode.
+    async function f() {
+        const await = 3
+              ~~~~~
+!!! error TS1359: Identifier expected. 'await' is a reserved word that cannot be used here.
+    }
+    function* g() {
+        const yield = 4
+              ~~~~~
+!!! error TS1214: Identifier expected. 'yield' is a reserved word in strict mode. Modules are automatically in strict mode.
+    }
+    class C {
+        #constructor = 5
+        ~~~~~~~~~~~~
+!!! error TS18012: '#constructor' is a reserved word.
+        deleted() {
+            function container(f) {
+                delete f
+                       ~
+!!! error TS1102: 'delete' cannot be called on an identifier in strict mode.
+            }
+            var g = 6
+            delete g
+                   ~
+!!! error TS1102: 'delete' cannot be called on an identifier in strict mode.
+            delete container
+                   ~~~~~~~~~
+!!! error TS1102: 'delete' cannot be called on an identifier in strict mode.
+        }
+        evalArguments() {
+            const eval = 7
+                  ~~~~
+!!! error TS1210: Code contained in a class is evaluated in JavaScript's strict mode which does not allow this use of 'eval'. For more information, see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Strict_mode.
+            const arguments = 8
+                  ~~~~~~~~~
+!!! error TS1210: Code contained in a class is evaluated in JavaScript's strict mode which does not allow this use of 'arguments'. For more information, see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Strict_mode.
+        }
+        withOctal() {
+            const redundant = 010
+                              ~~~
+!!! error TS1121: Octal literals are not allowed in strict mode.
+            with (redundant) {
+            ~~~~
+!!! error TS1101: 'with' statements are not allowed in strict mode.
+                return toFixed()
+            }
+        }
+        label() {
+            for(;;) {
+                label: var x = 1
+                ~~~~~
+!!! error TS1344: 'A label is not allowed here.
+                break label
+            }
+            return x
+        }
+    }
+    const eval = 9
+          ~~~~
+!!! error TS1215: Invalid use of 'eval'. Modules are automatically in strict mode.
+    const arguments = 10
+          ~~~~~~~~~
+!!! error TS1215: Invalid use of 'arguments'. Modules are automatically in strict mode.
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/plainJSBinderErrors.js b/tests/baselines/reference/plainJSBinderErrors.js
new file mode 100644
index 0000000000000..5f8f3138a64c5
--- /dev/null
+++ b/tests/baselines/reference/plainJSBinderErrors.js
@@ -0,0 +1,84 @@
+//// [plainJSBinderErrors.js]
+export default 12
+export default 13
+const await = 1
+const yield = 2
+async function f() {
+    const await = 3
+}
+function* g() {
+    const yield = 4
+}
+class C {
+    #constructor = 5
+    deleted() {
+        function container(f) {
+            delete f
+        }
+        var g = 6
+        delete g
+        delete container
+    }
+    evalArguments() {
+        const eval = 7
+        const arguments = 8
+    }
+    withOctal() {
+        const redundant = 010
+        with (redundant) {
+            return toFixed()
+        }
+    }
+    label() {
+        for(;;) {
+            label: var x = 1
+            break label
+        }
+        return x
+    }
+}
+const eval = 9
+const arguments = 10
+
+
+//// [plainJSBinderErrors.js]
+export default 12;
+export default 13;
+const await = 1;
+const yield = 2;
+async function f() {
+    const await = 3;
+}
+function* g() {
+    const yield = 4;
+}
+class C {
+    #constructor = 5;
+    deleted() {
+        function container(f) {
+            delete f;
+        }
+        var g = 6;
+        delete g;
+        delete container;
+    }
+    evalArguments() {
+        const eval = 7;
+        const arguments = 8;
+    }
+    withOctal() {
+        const redundant = 010;
+        with (redundant) {
+            return toFixed();
+        }
+    }
+    label() {
+        for (;;) {
+            label: var x = 1;
+            break label;
+        }
+        return x;
+    }
+}
+const eval = 9;
+const arguments = 10;
diff --git a/tests/baselines/reference/plainJSBinderErrors.symbols b/tests/baselines/reference/plainJSBinderErrors.symbols
new file mode 100644
index 0000000000000..55b2866141718
--- /dev/null
+++ b/tests/baselines/reference/plainJSBinderErrors.symbols
@@ -0,0 +1,86 @@
+=== tests/cases/conformance/salsa/plainJSBinderErrors.js ===
+export default 12
+export default 13
+const await = 1
+>await : Symbol(await, Decl(plainJSBinderErrors.js, 2, 5))
+
+const yield = 2
+>yield : Symbol(yield, Decl(plainJSBinderErrors.js, 3, 5))
+
+async function f() {
+>f : Symbol(f, Decl(plainJSBinderErrors.js, 3, 15))
+
+    const await = 3
+>await : Symbol(await, Decl(plainJSBinderErrors.js, 5, 9))
+}
+function* g() {
+>g : Symbol(g, Decl(plainJSBinderErrors.js, 6, 1))
+
+    const yield = 4
+>yield : Symbol(yield, Decl(plainJSBinderErrors.js, 8, 9))
+}
+class C {
+>C : Symbol(C, Decl(plainJSBinderErrors.js, 9, 1))
+
+    #constructor = 5
+>#constructor : Symbol(C.#constructor, Decl(plainJSBinderErrors.js, 10, 9))
+
+    deleted() {
+>deleted : Symbol(C.deleted, Decl(plainJSBinderErrors.js, 11, 20))
+
+        function container(f) {
+>container : Symbol(container, Decl(plainJSBinderErrors.js, 12, 15))
+>f : Symbol(f, Decl(plainJSBinderErrors.js, 13, 27))
+
+            delete f
+>f : Symbol(f, Decl(plainJSBinderErrors.js, 13, 27))
+        }
+        var g = 6
+>g : Symbol(g, Decl(plainJSBinderErrors.js, 16, 11))
+
+        delete g
+>g : Symbol(g, Decl(plainJSBinderErrors.js, 16, 11))
+
+        delete container
+>container : Symbol(container, Decl(plainJSBinderErrors.js, 12, 15))
+    }
+    evalArguments() {
+>evalArguments : Symbol(C.evalArguments, Decl(plainJSBinderErrors.js, 19, 5))
+
+        const eval = 7
+>eval : Symbol(eval, Decl(plainJSBinderErrors.js, 21, 13))
+
+        const arguments = 8
+>arguments : Symbol(arguments, Decl(plainJSBinderErrors.js, 22, 13))
+    }
+    withOctal() {
+>withOctal : Symbol(C.withOctal, Decl(plainJSBinderErrors.js, 23, 5))
+
+        const redundant = 010
+>redundant : Symbol(redundant, Decl(plainJSBinderErrors.js, 25, 13))
+
+        with (redundant) {
+>redundant : Symbol(redundant, Decl(plainJSBinderErrors.js, 25, 13))
+
+            return toFixed()
+        }
+    }
+    label() {
+>label : Symbol(C.label, Decl(plainJSBinderErrors.js, 29, 5))
+
+        for(;;) {
+            label: var x = 1
+>x : Symbol(x, Decl(plainJSBinderErrors.js, 32, 22))
+
+            break label
+        }
+        return x
+>x : Symbol(x, Decl(plainJSBinderErrors.js, 32, 22))
+    }
+}
+const eval = 9
+>eval : Symbol(eval, Decl(plainJSBinderErrors.js, 38, 5))
+
+const arguments = 10
+>arguments : Symbol(arguments, Decl(plainJSBinderErrors.js, 39, 5))
+
diff --git a/tests/baselines/reference/plainJSBinderErrors.types b/tests/baselines/reference/plainJSBinderErrors.types
new file mode 100644
index 0000000000000..29c4be2c11a20
--- /dev/null
+++ b/tests/baselines/reference/plainJSBinderErrors.types
@@ -0,0 +1,105 @@
+=== tests/cases/conformance/salsa/plainJSBinderErrors.js ===
+export default 12
+export default 13
+const await = 1
+>await : 1
+>1 : 1
+
+const yield = 2
+>yield : 2
+>2 : 2
+
+async function f() {
+>f : () => Promise<void>
+
+    const await = 3
+>await : 3
+>3 : 3
+}
+function* g() {
+>g : () => Generator<never, void, unknown>
+
+    const yield = 4
+>yield : 4
+>4 : 4
+}
+class C {
+>C : C
+
+    #constructor = 5
+>#constructor : number
+>5 : 5
+
+    deleted() {
+>deleted : () => void
+
+        function container(f) {
+>container : (f: any) => void
+>f : any
+
+            delete f
+>delete f : boolean
+>f : any
+        }
+        var g = 6
+>g : number
+>6 : 6
+
+        delete g
+>delete g : boolean
+>g : number
+
+        delete container
+>delete container : boolean
+>container : (f: any) => void
+    }
+    evalArguments() {
+>evalArguments : () => void
+
+        const eval = 7
+>eval : 7
+>7 : 7
+
+        const arguments = 8
+>arguments : 8
+>8 : 8
+    }
+    withOctal() {
+>withOctal : () => any
+
+        const redundant = 010
+>redundant : 10
+>010 : 10
+
+        with (redundant) {
+>redundant : 10
+
+            return toFixed()
+>toFixed() : any
+>toFixed : any
+        }
+    }
+    label() {
+>label : () => number
+
+        for(;;) {
+            label: var x = 1
+>label : any
+>x : number
+>1 : 1
+
+            break label
+>label : any
+        }
+        return x
+>x : number
+    }
+}
+const eval = 9
+>eval : 9
+>9 : 9
+
+const arguments = 10
+>arguments : 10
+>10 : 10
+
diff --git a/tests/baselines/reference/plainJSModuleStrict.errors.txt b/tests/baselines/reference/plainJSModuleStrict.errors.txt
new file mode 100644
index 0000000000000..fa3b605f9ed12
--- /dev/null
+++ b/tests/baselines/reference/plainJSModuleStrict.errors.txt
@@ -0,0 +1,37 @@
+tests/cases/conformance/salsa/plainJSMultipleDefaultExport.js(1,1): error TS2528: A module cannot have multiple default exports.
+tests/cases/conformance/salsa/plainJSMultipleDefaultExport.js(2,1): error TS2528: A module cannot have multiple default exports.
+tests/cases/conformance/salsa/plainJSMultipleDefaultExport.js(3,7): error TS1262: Identifier expected. 'await' is a reserved word at the top-level of a module.
+tests/cases/conformance/salsa/plainJSMultipleDefaultExport.js(4,7): error TS1214: Identifier expected. 'yield' is a reserved word in strict mode. Modules are automatically in strict mode.
+tests/cases/conformance/salsa/plainJSMultipleDefaultExport.js(6,11): error TS1359: Identifier expected. 'await' is a reserved word that cannot be used here.
+tests/cases/conformance/salsa/plainJSMultipleDefaultExport.js(9,11): error TS1214: Identifier expected. 'yield' is a reserved word in strict mode. Modules are automatically in strict mode.
+
+
+==== tests/cases/conformance/salsa/plainJSMultipleDefaultExport.js (6 errors) ====
+    export default 12
+    ~~~~~~~~~~~~~~~~~
+!!! error TS2528: A module cannot have multiple default exports.
+!!! related TS2753 tests/cases/conformance/salsa/plainJSMultipleDefaultExport.js:2:1: Another export default is here.
+    export default 13
+    ~~~~~~~~~~~~~~~~~
+!!! error TS2528: A module cannot have multiple default exports.
+!!! related TS2752 tests/cases/conformance/salsa/plainJSMultipleDefaultExport.js:1:1: The first export default is here.
+    const await = 1
+          ~~~~~
+!!! error TS1262: Identifier expected. 'await' is a reserved word at the top-level of a module.
+    const yield = 2
+          ~~~~~
+!!! error TS1214: Identifier expected. 'yield' is a reserved word in strict mode. Modules are automatically in strict mode.
+    async function f() {
+        const await = 3
+              ~~~~~
+!!! error TS1359: Identifier expected. 'await' is a reserved word that cannot be used here.
+    }
+    function* g() {
+        const yield = 4
+              ~~~~~
+!!! error TS1214: Identifier expected. 'yield' is a reserved word in strict mode. Modules are automatically in strict mode.
+    }
+    class C {
+        #constructor = 1
+    }
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/plainJSModuleStrict.js b/tests/baselines/reference/plainJSModuleStrict.js
new file mode 100644
index 0000000000000..4a6d28c392d6d
--- /dev/null
+++ b/tests/baselines/reference/plainJSModuleStrict.js
@@ -0,0 +1,30 @@
+//// [plainJSMultipleDefaultExport.js]
+export default 12
+export default 13
+const await = 1
+const yield = 2
+async function f() {
+    const await = 3
+}
+function* g() {
+    const yield = 4
+}
+class C {
+    #constructor = 1
+}
+
+
+//// [plainJSMultipleDefaultExport.js]
+export default 12;
+export default 13;
+const await = 1;
+const yield = 2;
+async function f() {
+    const await = 3;
+}
+function* g() {
+    const yield = 4;
+}
+class C {
+    #constructor = 1;
+}
diff --git a/tests/baselines/reference/plainJSModuleStrict.symbols b/tests/baselines/reference/plainJSModuleStrict.symbols
new file mode 100644
index 0000000000000..2b572478c42aa
--- /dev/null
+++ b/tests/baselines/reference/plainJSModuleStrict.symbols
@@ -0,0 +1,28 @@
+=== tests/cases/conformance/salsa/plainJSMultipleDefaultExport.js ===
+export default 12
+export default 13
+const await = 1
+>await : Symbol(await, Decl(plainJSMultipleDefaultExport.js, 2, 5))
+
+const yield = 2
+>yield : Symbol(yield, Decl(plainJSMultipleDefaultExport.js, 3, 5))
+
+async function f() {
+>f : Symbol(f, Decl(plainJSMultipleDefaultExport.js, 3, 15))
+
+    const await = 3
+>await : Symbol(await, Decl(plainJSMultipleDefaultExport.js, 5, 9))
+}
+function* g() {
+>g : Symbol(g, Decl(plainJSMultipleDefaultExport.js, 6, 1))
+
+    const yield = 4
+>yield : Symbol(yield, Decl(plainJSMultipleDefaultExport.js, 8, 9))
+}
+class C {
+>C : Symbol(C, Decl(plainJSMultipleDefaultExport.js, 9, 1))
+
+    #constructor = 1
+>#constructor : Symbol(C.#constructor, Decl(plainJSMultipleDefaultExport.js, 10, 9))
+}
+
diff --git a/tests/baselines/reference/plainJSModuleStrict.types b/tests/baselines/reference/plainJSModuleStrict.types
new file mode 100644
index 0000000000000..51d45840d0fd5
--- /dev/null
+++ b/tests/baselines/reference/plainJSModuleStrict.types
@@ -0,0 +1,33 @@
+=== tests/cases/conformance/salsa/plainJSMultipleDefaultExport.js ===
+export default 12
+export default 13
+const await = 1
+>await : 1
+>1 : 1
+
+const yield = 2
+>yield : 2
+>2 : 2
+
+async function f() {
+>f : () => Promise<void>
+
+    const await = 3
+>await : 3
+>3 : 3
+}
+function* g() {
+>g : () => Generator<never, void, unknown>
+
+    const yield = 4
+>yield : 4
+>4 : 4
+}
+class C {
+>C : C
+
+    #constructor = 1
+>#constructor : number
+>1 : 1
+}
+
diff --git a/tests/baselines/reference/plainJSRedeclare.errors.txt b/tests/baselines/reference/plainJSRedeclare.errors.txt
new file mode 100644
index 0000000000000..c47a3f90d0b29
--- /dev/null
+++ b/tests/baselines/reference/plainJSRedeclare.errors.txt
@@ -0,0 +1,13 @@
+tests/cases/conformance/salsa/plainJSRedeclare.js(1,7): error TS2451: Cannot redeclare block-scoped variable 'orbitol'.
+tests/cases/conformance/salsa/plainJSRedeclare.js(2,5): error TS2451: Cannot redeclare block-scoped variable 'orbitol'.
+
+
+==== tests/cases/conformance/salsa/plainJSRedeclare.js (2 errors) ====
+    const orbitol = 1
+          ~~~~~~~
+!!! error TS2451: Cannot redeclare block-scoped variable 'orbitol'.
+    var orbitol = 1 + false
+        ~~~~~~~
+!!! error TS2451: Cannot redeclare block-scoped variable 'orbitol'.
+    orbitol.toExponential()
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/plainJSRedeclare.js b/tests/baselines/reference/plainJSRedeclare.js
new file mode 100644
index 0000000000000..32b3249fe6773
--- /dev/null
+++ b/tests/baselines/reference/plainJSRedeclare.js
@@ -0,0 +1,10 @@
+//// [plainJSRedeclare.js]
+const orbitol = 1
+var orbitol = 1 + false
+orbitol.toExponential()
+
+
+//// [plainJSRedeclare.js]
+var orbitol = 1;
+var orbitol = 1 + false;
+orbitol.toExponential();
diff --git a/tests/baselines/reference/plainJSRedeclare.symbols b/tests/baselines/reference/plainJSRedeclare.symbols
new file mode 100644
index 0000000000000..5214b68b4fefd
--- /dev/null
+++ b/tests/baselines/reference/plainJSRedeclare.symbols
@@ -0,0 +1,12 @@
+=== tests/cases/conformance/salsa/plainJSRedeclare.js ===
+const orbitol = 1
+>orbitol : Symbol(orbitol, Decl(plainJSRedeclare.js, 0, 5))
+
+var orbitol = 1 + false
+>orbitol : Symbol(orbitol, Decl(plainJSRedeclare.js, 1, 3))
+
+orbitol.toExponential()
+>orbitol.toExponential : Symbol(Number.toExponential, Decl(lib.es5.d.ts, --, --))
+>orbitol : Symbol(orbitol, Decl(plainJSRedeclare.js, 0, 5))
+>toExponential : Symbol(Number.toExponential, Decl(lib.es5.d.ts, --, --))
+
diff --git a/tests/baselines/reference/plainJSRedeclare.types b/tests/baselines/reference/plainJSRedeclare.types
new file mode 100644
index 0000000000000..0962bb3221fd7
--- /dev/null
+++ b/tests/baselines/reference/plainJSRedeclare.types
@@ -0,0 +1,17 @@
+=== tests/cases/conformance/salsa/plainJSRedeclare.js ===
+const orbitol = 1
+>orbitol : 1
+>1 : 1
+
+var orbitol = 1 + false
+>orbitol : any
+>1 + false : any
+>1 : 1
+>false : false
+
+orbitol.toExponential()
+>orbitol.toExponential() : string
+>orbitol.toExponential : (fractionDigits?: number) => string
+>orbitol : 1
+>toExponential : (fractionDigits?: number) => string
+
diff --git a/tests/baselines/reference/plainJSRedeclare2.errors.txt b/tests/baselines/reference/plainJSRedeclare2.errors.txt
new file mode 100644
index 0000000000000..ca4ef82bbc756
--- /dev/null
+++ b/tests/baselines/reference/plainJSRedeclare2.errors.txt
@@ -0,0 +1,16 @@
+tests/cases/conformance/salsa/plainJSRedeclare.js(1,7): error TS2451: Cannot redeclare block-scoped variable 'orbitol'.
+tests/cases/conformance/salsa/plainJSRedeclare.js(2,5): error TS2451: Cannot redeclare block-scoped variable 'orbitol'.
+tests/cases/conformance/salsa/plainJSRedeclare.js(2,15): error TS2365: Operator '+' cannot be applied to types 'number' and 'boolean'.
+
+
+==== tests/cases/conformance/salsa/plainJSRedeclare.js (3 errors) ====
+    const orbitol = 1
+          ~~~~~~~
+!!! error TS2451: Cannot redeclare block-scoped variable 'orbitol'.
+    var orbitol = 1 + false
+        ~~~~~~~
+!!! error TS2451: Cannot redeclare block-scoped variable 'orbitol'.
+                  ~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'number' and 'boolean'.
+    orbitol.toExponential()
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/plainJSRedeclare2.js b/tests/baselines/reference/plainJSRedeclare2.js
new file mode 100644
index 0000000000000..32b3249fe6773
--- /dev/null
+++ b/tests/baselines/reference/plainJSRedeclare2.js
@@ -0,0 +1,10 @@
+//// [plainJSRedeclare.js]
+const orbitol = 1
+var orbitol = 1 + false
+orbitol.toExponential()
+
+
+//// [plainJSRedeclare.js]
+var orbitol = 1;
+var orbitol = 1 + false;
+orbitol.toExponential();
diff --git a/tests/baselines/reference/plainJSRedeclare2.symbols b/tests/baselines/reference/plainJSRedeclare2.symbols
new file mode 100644
index 0000000000000..5214b68b4fefd
--- /dev/null
+++ b/tests/baselines/reference/plainJSRedeclare2.symbols
@@ -0,0 +1,12 @@
+=== tests/cases/conformance/salsa/plainJSRedeclare.js ===
+const orbitol = 1
+>orbitol : Symbol(orbitol, Decl(plainJSRedeclare.js, 0, 5))
+
+var orbitol = 1 + false
+>orbitol : Symbol(orbitol, Decl(plainJSRedeclare.js, 1, 3))
+
+orbitol.toExponential()
+>orbitol.toExponential : Symbol(Number.toExponential, Decl(lib.es5.d.ts, --, --))
+>orbitol : Symbol(orbitol, Decl(plainJSRedeclare.js, 0, 5))
+>toExponential : Symbol(Number.toExponential, Decl(lib.es5.d.ts, --, --))
+
diff --git a/tests/baselines/reference/plainJSRedeclare2.types b/tests/baselines/reference/plainJSRedeclare2.types
new file mode 100644
index 0000000000000..0962bb3221fd7
--- /dev/null
+++ b/tests/baselines/reference/plainJSRedeclare2.types
@@ -0,0 +1,17 @@
+=== tests/cases/conformance/salsa/plainJSRedeclare.js ===
+const orbitol = 1
+>orbitol : 1
+>1 : 1
+
+var orbitol = 1 + false
+>orbitol : any
+>1 + false : any
+>1 : 1
+>false : false
+
+orbitol.toExponential()
+>orbitol.toExponential() : string
+>orbitol.toExponential : (fractionDigits?: number) => string
+>orbitol : 1
+>toExponential : (fractionDigits?: number) => string
+
diff --git a/tests/baselines/reference/plainJSRedeclare3.js b/tests/baselines/reference/plainJSRedeclare3.js
new file mode 100644
index 0000000000000..32b3249fe6773
--- /dev/null
+++ b/tests/baselines/reference/plainJSRedeclare3.js
@@ -0,0 +1,10 @@
+//// [plainJSRedeclare.js]
+const orbitol = 1
+var orbitol = 1 + false
+orbitol.toExponential()
+
+
+//// [plainJSRedeclare.js]
+var orbitol = 1;
+var orbitol = 1 + false;
+orbitol.toExponential();
diff --git a/tests/baselines/reference/plainJSRedeclare3.symbols b/tests/baselines/reference/plainJSRedeclare3.symbols
new file mode 100644
index 0000000000000..5214b68b4fefd
--- /dev/null
+++ b/tests/baselines/reference/plainJSRedeclare3.symbols
@@ -0,0 +1,12 @@
+=== tests/cases/conformance/salsa/plainJSRedeclare.js ===
+const orbitol = 1
+>orbitol : Symbol(orbitol, Decl(plainJSRedeclare.js, 0, 5))
+
+var orbitol = 1 + false
+>orbitol : Symbol(orbitol, Decl(plainJSRedeclare.js, 1, 3))
+
+orbitol.toExponential()
+>orbitol.toExponential : Symbol(Number.toExponential, Decl(lib.es5.d.ts, --, --))
+>orbitol : Symbol(orbitol, Decl(plainJSRedeclare.js, 0, 5))
+>toExponential : Symbol(Number.toExponential, Decl(lib.es5.d.ts, --, --))
+
diff --git a/tests/baselines/reference/plainJSRedeclare3.types b/tests/baselines/reference/plainJSRedeclare3.types
new file mode 100644
index 0000000000000..0962bb3221fd7
--- /dev/null
+++ b/tests/baselines/reference/plainJSRedeclare3.types
@@ -0,0 +1,17 @@
+=== tests/cases/conformance/salsa/plainJSRedeclare.js ===
+const orbitol = 1
+>orbitol : 1
+>1 : 1
+
+var orbitol = 1 + false
+>orbitol : any
+>1 + false : any
+>1 : 1
+>false : false
+
+orbitol.toExponential()
+>orbitol.toExponential() : string
+>orbitol.toExponential : (fractionDigits?: number) => string
+>orbitol : 1
+>toExponential : (fractionDigits?: number) => string
+
diff --git a/tests/baselines/reference/plainJSReservedStrict.errors.txt b/tests/baselines/reference/plainJSReservedStrict.errors.txt
new file mode 100644
index 0000000000000..db4714a10c194
--- /dev/null
+++ b/tests/baselines/reference/plainJSReservedStrict.errors.txt
@@ -0,0 +1,13 @@
+tests/cases/conformance/salsa/plainJSReservedStrict.js(2,7): error TS1100: Invalid use of 'eval' in strict mode.
+tests/cases/conformance/salsa/plainJSReservedStrict.js(3,7): error TS1100: Invalid use of 'arguments' in strict mode.
+
+
+==== tests/cases/conformance/salsa/plainJSReservedStrict.js (2 errors) ====
+    "use strict"
+    const eval = 1
+          ~~~~
+!!! error TS1100: Invalid use of 'eval' in strict mode.
+    const arguments = 2
+          ~~~~~~~~~
+!!! error TS1100: Invalid use of 'arguments' in strict mode.
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/plainJSReservedStrict.js b/tests/baselines/reference/plainJSReservedStrict.js
new file mode 100644
index 0000000000000..9f35d353afc6a
--- /dev/null
+++ b/tests/baselines/reference/plainJSReservedStrict.js
@@ -0,0 +1,10 @@
+//// [plainJSReservedStrict.js]
+"use strict"
+const eval = 1
+const arguments = 2
+
+
+//// [plainJSReservedStrict.js]
+"use strict";
+const eval = 1;
+const arguments = 2;
diff --git a/tests/baselines/reference/plainJSReservedStrict.symbols b/tests/baselines/reference/plainJSReservedStrict.symbols
new file mode 100644
index 0000000000000..e89d121657979
--- /dev/null
+++ b/tests/baselines/reference/plainJSReservedStrict.symbols
@@ -0,0 +1,8 @@
+=== tests/cases/conformance/salsa/plainJSReservedStrict.js ===
+"use strict"
+const eval = 1
+>eval : Symbol(eval, Decl(plainJSReservedStrict.js, 1, 5))
+
+const arguments = 2
+>arguments : Symbol(arguments, Decl(plainJSReservedStrict.js, 2, 5))
+
diff --git a/tests/baselines/reference/plainJSReservedStrict.types b/tests/baselines/reference/plainJSReservedStrict.types
new file mode 100644
index 0000000000000..f4462e1cdab91
--- /dev/null
+++ b/tests/baselines/reference/plainJSReservedStrict.types
@@ -0,0 +1,12 @@
+=== tests/cases/conformance/salsa/plainJSReservedStrict.js ===
+"use strict"
+>"use strict" : "use strict"
+
+const eval = 1
+>eval : 1
+>1 : 1
+
+const arguments = 2
+>arguments : 2
+>2 : 2
+
diff --git a/tests/cases/conformance/salsa/plainJSBinderErrors.ts b/tests/cases/conformance/salsa/plainJSBinderErrors.ts
new file mode 100644
index 0000000000000..d2019e3f78b2f
--- /dev/null
+++ b/tests/cases/conformance/salsa/plainJSBinderErrors.ts
@@ -0,0 +1,44 @@
+// @outdir: out/
+// @target: esnext
+// @allowJS: true
+// @filename: plainJSBinderErrors.js
+export default 12
+export default 13
+const await = 1
+const yield = 2
+async function f() {
+    const await = 3
+}
+function* g() {
+    const yield = 4
+}
+class C {
+    #constructor = 5
+    deleted() {
+        function container(f) {
+            delete f
+        }
+        var g = 6
+        delete g
+        delete container
+    }
+    evalArguments() {
+        const eval = 7
+        const arguments = 8
+    }
+    withOctal() {
+        const redundant = 010
+        with (redundant) {
+            return toFixed()
+        }
+    }
+    label() {
+        for(;;) {
+            label: var x = 1
+            break label
+        }
+        return x
+    }
+}
+const eval = 9
+const arguments = 10
diff --git a/tests/cases/conformance/salsa/plainJSRedeclare.ts b/tests/cases/conformance/salsa/plainJSRedeclare.ts
new file mode 100644
index 0000000000000..be6831d0cdf12
--- /dev/null
+++ b/tests/cases/conformance/salsa/plainJSRedeclare.ts
@@ -0,0 +1,6 @@
+// @outdir: out/
+// @allowJS: true
+// @filename: plainJSRedeclare.js
+const orbitol = 1
+var orbitol = 1 + false
+orbitol.toExponential()
diff --git a/tests/cases/conformance/salsa/plainJSRedeclare2.ts b/tests/cases/conformance/salsa/plainJSRedeclare2.ts
new file mode 100644
index 0000000000000..7409b6c8fe071
--- /dev/null
+++ b/tests/cases/conformance/salsa/plainJSRedeclare2.ts
@@ -0,0 +1,7 @@
+// @outdir: out/
+// @allowJS: true
+// @checkJS: true
+// @filename: plainJSRedeclare.js
+const orbitol = 1
+var orbitol = 1 + false
+orbitol.toExponential()
diff --git a/tests/cases/conformance/salsa/plainJSRedeclare3.ts b/tests/cases/conformance/salsa/plainJSRedeclare3.ts
new file mode 100644
index 0000000000000..1327fcfc1777c
--- /dev/null
+++ b/tests/cases/conformance/salsa/plainJSRedeclare3.ts
@@ -0,0 +1,7 @@
+// @outdir: out/
+// @allowJS: true
+// @checkJS: false
+// @filename: plainJSRedeclare.js
+const orbitol = 1
+var orbitol = 1 + false
+orbitol.toExponential()
diff --git a/tests/cases/conformance/salsa/plainJSReservedStrict.ts b/tests/cases/conformance/salsa/plainJSReservedStrict.ts
new file mode 100644
index 0000000000000..fbd654927d1ea
--- /dev/null
+++ b/tests/cases/conformance/salsa/plainJSReservedStrict.ts
@@ -0,0 +1,7 @@
+// @outdir: out/
+// @target: esnext
+// @allowJS: true
+// @filename: plainJSReservedStrict.js
+"use strict"
+const eval = 1
+const arguments = 2