Sumer.js

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

Sumer.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 Sumer = require('@meterio/sumer-js'); // in Node.js
const cUsdtAddress = Sumer.util.getAddress(Sumer.cUSDT);

(async function() {

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

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

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

Sumer Protocol

Simple methods for using the Sumer protocol.

const sumer = new Sumer(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 Sumer protocol...');
  const trx = await sumer.supply(Sumer.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/@meterio/sumer-js@latest/dist/browser/sumer.min.js"></script>

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

Node.js

npm install @meterio/sumer-js

const Sumer = require('@meterio/sumer-js');

// or, when using ES6

import Sumer from '@meterio/sumer-js';

More Code Examples

See the docblock comments above each function definition or the official Sumer.js Documentation.

Instance Creation

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

var sumer = new Sumer(window.ethereum); // web browser

var sumer = new Sumer('http://127.0.0.1:8545'); // HTTP provider

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

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

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

// Init with HD mnemonic (server side)
var sumer = new Sumer('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(Sumer.DAI, Sumer.ETH, Sumer.cETH);
// DAI, ETH, cETH

const cUsdtAddress = Sumer.util.getAddress(Sumer.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 sumer.borrow(Sumer.DAI, '1000000000000000000', { mantissa: true });

// `mantissa` defaults to false if it is not specified or if an options object is not passed
await sumer.borrow(Sumer.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 `Sumer._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 `Sumer.eth.trx` (server side)
  mnemonic,   // String, meant to be used with `Sumer.eth.trx` (server side)
};

API

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

• Sumer.api.account
• Sumer.api.cToken
• Sumer.api.marketHistory
• Sumer.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 Sumer.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 === Sumer.cDAI) {
          daiBorrowBalance = +tok.borrow_balance_underlying.value;
        }
      });
    });
  }

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

main().catch(console.error);

Test

Tests are available in ./test/*.test.js. The tests are configured in ./test/index.js. Methods are tested using a forked chain using ganache-core. A JSON RPC provider URL needs to be configured as an environment variable before running the tests (MAINNET_PROVIDER_URL). Archive state must be available to run the tests. For free archive node access, get a provider URL from Alchemy.

## Run all tests
npm test

## Run a single test (Mocha JS grep option)
npm test -- -g 'runs eth.getBalance'

Build for Node.js & Web Browser

git clone [email protected]:meterio/sumer-js.git
cd sumer-js/
npm install
npm run build

Web Browser Build

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

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

Node.js Build

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

// Public NPM build
const Sumer = require('@meterio/sumer-js');