Node.js 1inch v4.0 api swap example

1inch_swap.js

require('dotenv').config()
const fetch = require('isomorphic-fetch')
const { providers, BigNumber, Wallet } = require('ethers')
const { formatUnits, parseUnits } = require('ethers/lib/utils')

const priv = process.env.PRIVATE_KEY

const rpcUrls = {
  ethereum: 'https://mainnet.infura.io',
  polygon: 'https://polygon.infura.io',
  xdai: 'https://xdai.infura.io'
}

const slugToChainId = {
  ethereum: 1,
  polygon: 137,
  xdai: 100
}

const tokenDecimals = {
  USDC: 6,
  ETH: 18
}

const addresses = {
  ethereum: {
    USDC: '0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48',
    ETH: '0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2'
  },
  polygon: {
    USDC: '0x2791Bca1f2de4661ED88A30C99A7a9449Aa84174',
    ETH: '0x7ceB23fD6bC0adD59E62ac25578270cFf1b9f619'
  },
  xdai: {
    USDC: '0xDDAfbb505ad214D7b80b1f830fcCc89B60fb7A83',
    ETH: '0x6A023CCd1ff6F2045C3309768eAd9E68F978f6e1'
  }
}

class OneInch {
  constructor () {
    this.baseUrl = 'https://api.1inch.exchange/v4.0'
  }

  async getQuote (config) {
    const { chainId, fromTokenAddress, toTokenAddress, amount } = config
    if (!chainId) {
      throw new Error('chainId is required')
    }
    if (!fromTokenAddress) {
      throw new Error('fromTokenAddrss is required')
    }
    if (!toTokenAddress) {
      throw new Error('toTokenAddress is required')
    }
    if (!amount) {
      throw new Error('amount is required')
    }
    const url = `${this.baseUrl}/${chainId}/quote?fromTokenAddress=${fromTokenAddress}&toTokenAddress=${toTokenAddress}&amount=${amount}`
    const result = await this.getJson(url)
    if (!result.toTokenAmount) {
      console.log(result)
      throw new Error('expected tx data')
    }

    const { toTokenAmount } = result

    return toTokenAmount
  }

  async getAllowance (config) {
    const { chainId, tokenAddress, walletAddress } = config
    if (!chainId) {
      throw new Error('chainId is required')
    }
    if (!tokenAddress) {
      throw new Error('tokenAddress required')
    }
    if (!walletAddress) {
      throw new Error('walletAddress is required')
    }

    const url = `${this.baseUrl}/${chainId}/approve/allowance?tokenAddress=${tokenAddress}&walletAddress=${walletAddress}`
    const result = await this.getJson(url)
    if (result.allowance === undefined) {
      console.log(result)
      throw new Error('expected tx data')
    }

    return result.allowance
  }

  async getApproveTx (config) {
    const { chainId, tokenAddress, amount } = config
    if (!chainId) {
      throw new Error('chainId is required')
    }
    if (!tokenAddress) {
      throw new Error('tokenAddress required')
    }
    if (!amount) {
      throw new Error('amount is required')
    }

    const url = `${this.baseUrl}/${chainId}/approve/transaction?&amount=${amount}&tokenAddress=${tokenAddress}`
    const result = await this.getJson(url)
    if (!result.data) {
      console.log(result)
      throw new Error('expected tx data')
    }

    const { data, to, value } = result

    return {
      data,
      to,
      value
    }
  }

  async getSwapTx (config) {
    const { chainId, fromTokenAddress, toTokenAddress, fromAddress, amount, slippage } = config
    if (!chainId) {
      throw new Error('chainId is required')
    }
    if (!fromTokenAddress) {
      throw new Error('fromTokenAddrss is required')
    }
    if (!toTokenAddress) {
      throw new Error('toTokenAddress is required')
    }
    if (!fromAddress) {
      throw new Error('fromAddress is required')
    }
    if (!amount) {
      throw new Error('amount is required')
    }
    if (!slippage) {
      throw new Error('slippage is required')
    }
    const url = `${this.baseUrl}/${chainId}/swap?fromTokenAddress=${fromTokenAddress}&toTokenAddress=${toTokenAddress}&amount=${amount}&fromAddress=${fromAddress}&slippage=${slippage}`
    const result = await this.getJson(url)
    if (!result.tx) {
      console.log(result)
      throw new Error('expected tx data')
    }

    const { data, to, value } = result.tx

    return {
      data,
      to,
      value
    }
  }

  async getJson (url) {
    const res = await fetch(url)
    const json = await res.json()
    if (!json) {
      throw new Error('no response')
    }
    if (json.error) {
      console.log(json)
      throw new Error(json.description || json.error)
    }

    return json
  }
}

async function main () {
  const chain = 'xdai'
  const rpcUrl = rpcUrls[chain]
  const provider = new providers.StaticJsonRpcProvider(rpcUrl)
  const wallet = new Wallet(priv, provider)

  const oneInch = new OneInch()

  const chainId = slugToChainId[chain]
  const fromToken = 'USDC'
  const toToken = 'ETH'
  const slippage = 1
  const walletAddress = await wallet.getAddress()
  const formattedAmount = '1'
  const amount = parseUnits(formattedAmount, tokenDecimals[fromToken]).toString()

  console.log('chain:', chain)
  console.log('fromToken:', fromToken)
  console.log('toToken:', toToken)
  console.log('amount:', formattedAmount)

  const fromTokenAddress = addresses[chain][fromToken]
  const toTokenAddress = addresses[chain][toToken]
  const toTokenAmount = await oneInch.getQuote({ chainId, fromTokenAddress, toTokenAddress, amount })
  const toTokenAmountFormatted = formatUnits(toTokenAmount, tokenDecimals[toToken])
  console.log(`toTokenAmount: ${toTokenAmountFormatted}`)

  const tokenAddress = fromTokenAddress
  const allowance = await oneInch.getAllowance({ chainId, tokenAddress, walletAddress })
  console.log('allowance:', allowance)
  if (BigNumber.from(allowance).lt(amount)) {
    const txData = await oneInch.getApproveTx({ chainId, tokenAddress, amount })
    console.log('approval data:', txData)

    const tx = await wallet.sendTransaction(txData)
    console.log('approval tx:', tx.hash)
    await tx.wait()
  }

  const fromAddress = walletAddress
  const txData = await oneInch.getSwapTx({ chainId, fromTokenAddress, toTokenAddress, fromAddress, amount, slippage })
  console.log('swap data:', txData)
  const tx = await wallet.sendTransaction(txData)
  console.log('swap tx:', tx.hash)
  await tx.wait()

  console.log('done')
}

main()
  .catch(console.error)