paraswap

ParaSwap SDK

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You can use this SDK in order to swap or pay using ERC-20 tokens.

We've built an example dApp that can found here https://github.com/paraswap/demo-dapp

You can also check a live example at: https://paraswap-sdk.netlify.com

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API docs are available here :

https://paraswapv2.docs.apiary.io

To use ParaSwap SDK :

Install the lib using npm or yarn

yarn install paraswap

Then on a Javascript file:

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

ES6 or TypeScript

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

To retrieve the list all available tokens:

const tokens = await paraSwap.getTokens();

To get the rate of a token pair using the API:

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,
);

Where priceRoute contains the rate and the distribution among exchanges, checkout the OptimalRates type for more details.

To get the rate of a token pair using the Price Feed Contract:

This can be used for trustless integrations, the

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

This is a schema that describes the data flow from price query to executing a Swap:

Also available at https://paraswap-achirecture.netlify.com

To get the allowance of an ERC20

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

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

To approve an ERC20

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

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

To build and sign a transaction

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);
  },
);

---

To run the example locally:

Created an .env file with these 2 env variables:

PROVIDER_URL=YOUR_PROVIDRER_URL_OR_INFURA_URL
NODE_ENV=production

run

yarn install paraswap

For local developement you can run

yarn dev

For production build:

yarn build

Which will generate a production build on "dist" folder