# XChainJS Cross-Chain Swap Example (THORChain)

#blockchain #web3 #webdev #programming

This example demonstrates how to perform a cross-chain crypto swap using XChainJS and THORChain.

It shows how to:

work with standardized asset representations
handle crypto amounts safely
request and execute a swap using a unified TypeScript API

The example is fully runnable and available both on GitHub and CodeSandbox.

🔗 Live Demo & Source Code

▶ Live demo (CodeSandbox):

https://codesandbox.io/p/devbox/github/xchainjs/xchainjs-lib/tree/master/examples/do-swap
📦 Source code (GitHub):

https://github.com/xchainjs/xchainjs-lib/tree/master/examples/do-swap

📌 What This Example Does

This project performs a cross-chain swap using THORChain liquidity pools.

It demonstrates:

how to define input and output assets
how to create and validate swap amounts
how to interact with THORChain via XChainJS
how to keep the code chain-agnostic

This example is useful for developers building:

crypto wallets
DeFi frontends
swap aggregators
backend swap services
cross-chain dashboards

🧰 Tech Stack

TypeScript
Node.js
XChainJS
THORChain
@xchainjs/xchain-util
@xchainjs/xchain-thorchain

📂 Project Location

Inside the XChainJS monorepo:

examples/
└─ do-swap/

🔄 How the Swap Flow Works

Input Asset

→ XChainJS Asset Utilities

→ THORChain Client

→ Swap Quote

→ Transaction Execution

→ Cross-Chain Swap

🧩 Core Concepts

Asset Representation

Assets are represented using a standardized format:

Examples:

BTC.BTC
ETH.ETH
THOR.RUNE

This format is parsed and validated using utilities from

@xchainjs/xchain-util.

Amount Handling

Crypto applications must correctly separate:

human-readable amounts
base-unit amounts

This example uses XChainJS utilities to avoid rounding and decimal errors,
which are common in DeFi applications.

⚙️ Installation

Clone the repository

git clone https://github.com/xchainjs/xchainjs-lib.git cd xchainjs-lib/examples/do-swap

Install dependencies

npm install

Run the example

npm start

🚀 Running in the Browser

You can also run this example instantly using CodeSandbox:

https://codesandbox.io/p/devbox/github/xchainjs/xchainjs-lib/tree/master/examples/do-swap

🧪 Code Example (Simplified)

import { assetFromString, assetAmount } from '@xchainjs/xchain-util'

const fromAsset = assetFromString('BTC.BTC')
const toAsset = assetFromString('ETH.ETH')

const amount = assetAmount(0.01)

if (!fromAsset || !toAsset) {
  throw new Error('Invalid asset')
}