Flash SDK 🧰

Set of tools for interaction with Flash protocol. See:

• usage examples for a good starting point for working with the SDK
• installation for instructions on how to setup SDK in a project
• modules for all available SDK classes/types/etc

Usage Examples

Swap one specific crypto to another

import { FlashClient, ViemWallet, Crypto, Amount } from '@swaps-io/flash-sdk';

// Initialize FlashClient
const projectId = 'sdk-example'; // Replace with a meaningful project ID
const wallet = await ViemWallet.fromPrivateKey('0x13...37');
const flash = new FlashClient({ projectId, wallet });
await flash.preload(); // Optional

// Select "from" & "to" cryptos by their chain ID & contract address
const fromCrypto = await flash.getCrypto({ id: Crypto.makeId('1', '0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2') });
const toCrypto = await flash.getCrypto({ id: Crypto.makeId('56', '0x7130d2A12B9BCbFAe4f2634d864A1Ee1Ce3Ead9c') });

// Get quote & submit swap for the selected cryptos & "from" amount
const fromAmount = Amount.fromDecimalString('12.34');
const quote = await flash.getQuote({ fromCrypto, fromAmount, toCrypto });
const swap = await flash.submitSwap({ quote });

Swap cryptos selected from the supported list

// Assuming FlashClient initialized
const flash: FlashClient = ...;

// Select "from" & "to" chains from supported list
const chains = await flash.getChains();
const [fromChain, toChain] = chains; // Example of chain selection

// Select "from" & "to" cryptos from supported list for each chain
const fromCryptos = await flash.getCryptos({ chain: fromChain });
const [fromCrypto] = fromCryptos; // Example of crypto selection
const toCryptos = await flash.getCryptos({ chain: toChain });
const [toCrypto] = toCryptos; // Example of crypto selection

// Get quote & submit swap for the selected cryptos & "from" amount
const fromAmount = Amount.fromDecimalString('12.34'); // Example
const quote = await flash.getQuote({ fromCrypto, fromAmount, toCrypto });
const swap = await flash.submitSwap({ quote });

Monitor submitted swap state

// Wait for ~ five seconds before next swap update
const swapUpdatePeriod = Duration.fromSeconds(5);

// Assuming FlashClient & quote are initialized
const flash: FlashClient = ...;
const quote: Quote = ...;
let swap = await flash.submitSwap({ quote });

// It's possible to handle "swap.state" manually,
// but easier with some helper getters, provided by "Swap"
while (swap.awaiting) {
  await swapUpdatePeriod.sleep();
  swap = await flash.getSwap({ swap });
}

// Check the result swap state
if (swap.completed) {
  // Swap completed - "from" crypto taken, "to" crypto received
  console.log(`Swap "${swap.hash}" completed`);
} else if (swap.slashable) {
  // Swap cancelled & slashable - "from" crypto taken, "to" crypto not received
  // The "to" actor's collateral should be taken to compensate the "from" crypto
  // This requires two transactions - in "to" & in "collateral" network (can be helped by liquidators)
  console.log(`Swap "${swap.hash}" cancelled and waiting for slash`);
} else {
  // Swap cancelled & not slashable - "from" crypto not taken, "to" crypto not received
  // Since nothing taken from the "from" actor, new swap can be created (even for the same quote)
  console.log(`Swap "${swap.hash}" cancelled`);
}

Development

Installation

The SDK installation process assumes that Node.js (version 22 is recommended) is installed on machine and a project where SDK is planned to be integrated is already created.

1. Install @swaps-io/flash-sdk as a usual NPM package dependency of the project
2. Install peer dependencies of SDK according to the needs of the project

Peer Dependencies

SDK dependencies are specified as "peer" ones, i.e. they are supposed to be installed explicitly in the project that uses this SDK. The safest option is to install all of them, however, some of them may be omitted if a set of specific use-cases is not needed for the project - see the table below for more details.

Dependency	Version	Required	When to Install
axios	1.6+	Yes	Always
qs	6.11+	Yes	Always
viem	2.1+	No [1]	EVM functionality in use & configured as provider (default) or wagmi or GnosisSafeWallet in use
ethers	6.9+	No [1]	EVM functionality in use & configured as provider or GnosisSafeWallet in use
wagmi	2.2+	No	WagmiWallet implementation in use
@tanstack/react-query	5.17+	No	WagmiWallet implementation in use
@safe-global/protocol-kit	5.0+	No	GnosisSafeWallet implementation in use (note - also requires viem)

Important notes:

• [1]: at least one of dependencies is required as a provider when EVM functionality is in use
• The package version must not exceed major part of what specified, i.e. version 5.0.0 won't work for 4.2+

Select EVM Provider

By default, SDK uses EVM provider based on viem library.

It's possible to use a different ready-made provider:

import { setEvmProvider, EthersEvmProvider } from '@swaps-io/flash-sdk';

// Before actively using SDK methods
setEvmProvider(new EthersEvmProvider());

Or implement a custom one:

import { IEvmProvider, setEvmProvider } from '@swaps-io/flash-sdk';

class CustomEvmProvider implements IEvmProvider { /* ... */ }

setEvmProvider(new CustomEvmProvider());

Known Issues

Optional dependency not resolved build error

Module not found: Error: Can't resolve '{optional-dependency}' in '{some-sdk-path}'. Did you mean './{optional-dependency}'?

This build error occurs during Webpack builds. Webpack tries to bundle all imported dependencies regardless of their actual usage. One possible resolution is to specify dependency as external in Webpack config referencing non-existing external package.

Resolution:

Say ethers is not needed in a project that uses Webpack via react-app-rewired. Specify it in externals of config-overrides.js:

module.exports = function override(config) {
  // ...
  config.externals = {
    ethers: 'never',
  };
  return config;
};

Axios initialization runtime error

Uncaught TypeError: axios_1.default.create is not a function

This runtime error is related to .cjs modules usage as mentioned in this GitHub comment.

Resolution:

Say Webpack is in use via react-app-rewired. Add the following rules override in config-overrides.js:

module.exports = function override(config) {
  // ...
  config.module.rules = config.module.rules.map((rule) => {
    if (rule.oneOf instanceof Array) {
      rule.oneOf[rule.oneOf.length - 1].exclude = [/\.(js|mjs|jsx|cjs|ts|tsx)$/, /\.html$/, /\.json$/];
    }
    return rule;
  });
  return config;
};