@lichangio/compound-js

Compound.js

A JavaScript SDK for Ethereum and the Compound Protocol. Wraps around Ethers.js. Works in the web browser and Node.js.

Compound.js Documentation

This SDK is in open beta, and is constantly under development. USE AT YOUR OWN RISK.

Ethereum Read & Write

JSON RPC based Ethereum read and write.

Read

const Compound = require('@compound-finance/compound-js'); // in Node.js
const cUsdtAddress = Compound.util.getAddress(Compound.cUSDT);

(async function() {

  let supplyRatePerBlock = await Compound.eth.read(
    cUsdtAddress,
    'function supplyRatePerBlock() returns (uint)',
    [], // [optional] parameters
    {}  // [optional] call options, provider, network, ethers.js "overrides"
  );

  console.log('USDT supplyRatePerBlock:', supplyRatePerBlock.toString());

})().catch(console.error);

Write

const toAddress = '0xa0df350d2637096571F7A701CBc1C5fdE30dF76A';

(async function() {

  const trx = await Compound.eth.trx(
    toAddress,
    'function send() external payable',
    [],
    {
      value: Compound._ethers.utils.parseEther('1.0'), // 1 ETH
      provider: window.ethereum, // in a web browser
    }
  );

  const toAddressEthBalance = await Compound.eth.getBalance(toAddress);

})().catch(console.error);

Compound Protocol

Simple methods for using the Compound protocol.

const compound = new Compound(window.ethereum); // in a web browser

// Ethers.js overrides are an optional 3rd parameter for `supply`
// const trxOptions = { gasLimit: 250000, mantissa: false };

(async function() {

  console.log('Supplying ETH to the Compound protocol...');
  const trx = await compound.supply(Compound.ETH, 1);
  console.log('Ethers.js transaction object', trx);

})().catch(console.error);

Install / Import

Web Browser

<script type="text/javascript" src="https://cdn.jsdelivr.net/npm/@compound-finance/compound-js@latest/dist/browser/compound.min.js"></script>

<script type="text/javascript">
  window.Compound; // or `Compound`
</script>

Node.js

npm install @compound-finance/compound-js

const Compound = require('@compound-finance/compound-js');

// or, when using ES6

import Compound from '@compound-finance/compound-js';

More Code Examples

• Node.js
• Web Browser

To run, boot Ganache fork of mainnet locally

Instance Creation

The following are valid Ethereum providers for initialization of the SDK.

var compound = new Compound(window.ethereum); // web browser

var compound = new Compound('http://127.0.0.1:8545'); // HTTP provider

var compound = new Compound(); // Uses Ethers.js fallback mainnet (for testing only)

var compound = new Compound('ropsten'); // Uses Ethers.js fallback (for testing only)

// Init with private key (server side)
var compound = new Compound('https://mainnet.infura.io/v3/_your_project_id_', {
  privateKey: '0x_your_private_key_', // preferably with environment variable
});

// Init with HD mnemonic (server side)
var compound = new Compound('mainnet' {
  mnemonic: 'clutch captain shoe...', // preferably with environment variable
});

Constants and Contract Addresses

Names of contracts, their addresses, ABIs, token decimals, and more can be found in /src/constants.ts. Addresses, for all networks, can be easily fetched using the getAddress function, combined with contract name constants.

console.log(Compound.DAI, Compound.ETH, Compound.cETH);
// DAI, ETH, cETH

const cUsdtAddress = Compound.util.getAddress(Compound.cUSDT);
// Mainnet cUSDT address. Second parameter can be a network like 'ropsten'.

Mantissas

Parameters of number values can be plain numbers or their scaled up mantissa values. There is a transaction option boolean to tell the SDK what the developer is passing.

// 1 Dai
await compound.borrow(Compound.DAI, '1000000000000000000', { mantissa: true });

// `mantissa` defaults to false if it is not specified or if an options object is not passed
await compound.borrow(Compound.DAI, 1, { mantissa: false });

Transaction Options

Each method that interacts with the blockchain accepts a final optional parameter for overrides, much like Ethers.js overrides.

// The options object itself and all options are optional
const trxOptions = {
  mantissa,   // Boolean, parameters array arg of 1 ETH would be '1000000000000000000' (true) vs 1 (false)
  abi,        // Definition string or an ABI array from a solc build
  provider,   // JSON RPC string, Web3 object, or Ethers.js fallback network (string)
  network,    // Ethers.js fallback network provider, "provider" has precedence over "network"
  from,       // Address that the Ethereum transaction is send from
  gasPrice,   // Ethers.js override `Compound._ethers.utils.parseUnits('10.0', 'gwei')`
  gasLimit,   // Ethers.js override - see https://docs.ethers.io/ethers.js/v5-beta/api-contract.html#overrides
  value,      // Number or string
  data,       // Number or string
  chainId,    // Number
  nonce,      // Number
  privateKey, // String, meant to be used with `Compound.eth.trx` (server side)
  mnemonic,   // String, meant to be used with `Compound.eth.trx` (server side)
};

API

The Compound API is accessible from Compound.js. The corresponding services are defined in the api namespace on the class.

• Compound.api.account
• Compound.api.cToken
• Compound.api.marketHistory
• Compound.api.governance

The governance method requires a second parameter (string) for the corresponding endpoint shown in the documentation.

• proposals
• voteReceipts
• accounts

Here is an example for using the account endpoint. The network parameter in the request body is optional and defaults to mainnet.

const main = async () => {
  const account = await Compound.api.account({
    "addresses": "0xB61C5971d9c0472befceFfbE662555B78284c307",
    "network": "ropsten"
  });

  let daiBorrowBalance = 0;
  if (Object.isExtensible(account) && account.accounts) {
    account.accounts.forEach((acc) => {
      acc.tokens.forEach((tok) => {
        if (tok.symbol === Compound.cDAI) {
          daiBorrowBalance = +tok.borrow_balance_underlying.value;
        }
      });
    });
  }

  console.log('daiBorrowBalance', daiBorrowBalance);
}

main().catch(console.error);

Build for Node.js & Web Browser

git clone [e-mail]:compound-finance/compound-js.git
cd compound-js/
npm install
npm run build

Web Browser Build

<!-- Local build (do `npm install` first) -->
<script type="text/javascript" src="./dist/browser/compound.min.js"></script>

<!-- Public NPM -> jsdeliver build -->
<script type="text/javascript" src="https://cdn.jsdelivr.net/npm/@compound-finance/compound-js@latest/dist/browser/compound.min.js"></script>

Node.js Build

// Local build (do `npm install` first)
const Compound = require('./dist/nodejs/index.js');

// Public NPM build
const Compound = require('@compound-finance/compound-js');