const { ParaSwap } = require('paraswap');
const paraSwap = new ParaSwap();

const tokens = await paraSwap.getTokens();

const srcToken = '0xeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee'; // ETH
const destToken = '0x89d24a6b4ccb1b6faa2625fe562bdd9a23260359'; // DAI
const srcAmount = '1000000000000000000'; //The source amount multiplied by its decimals: 10 ** 18 here

const priceRoute: OptimalRates = await paraSwap.getRate(
  srcToken,
  destToken,
  srcAmount,
);

const paraswapFeed = new ParaswapFeed(1);
const priceRoute: OptimalRates = await paraswapFeed.getRate(
  srcToken,
  destToken,
  srcAmount,
);

const paraSwap = new ParaSwap().setWeb3Provider(web3Provider);

const allowance = await paraSwap.getAllowance(userAddress, tokenAddress);

const paraSwap = new ParaSwap().setWeb3Provider(web3Provider);

const txHash = await paraSwap.approveToken(amount, userAddress, tokenAddress);

const srcToken = '0xeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee';
const destToken = '0x89d24a6b4ccb1b6faa2625fe562bdd9a23260359';
const srcAmount = '1000000000000000000'; //The source amount multiplied by its decimals
const senderAddress = '0xfceA770875E7e6f25E33CEa5188d12Ef234606b4';
const receiver = '0x8B4e846c90a2521F0D2733EaCb56760209EAd51A'; // Useful in case of swap and transfer
const referrer = 'my-company-or-nick-name';

const txParams = await paraSwap.buildTx(
  srcToken,
  destToken,
  srcAmount,
  destAmount,
  priceRoute,
  senderAddress,
  referrer,
  receiver,
);

web3.eth.sendTransaction(
  txParams,
  async (err: Error, transactionHash: string) => {
    if (err) {
      return this.setState({ error: err.toString(), loading: false });
    }
    console.log('transactionHash', transactionHash);
  },
);