yqrashawn / cfx-balance-checker

Solidity contract to batch balance checks in one call

Ethereum Balance Checker

A smart contract and library pair that allows you to check for multiple ERC20 and Ether balances across multiple addresses in a single RPC call.

Demo

You can find a demo over here: https://wbobeirne.github.io/eth-balance-checker-demo

The source for that demo is available here: https://github.com/wbobeirne/eth-balance-checker-demo

NPM Package

npm install --save eth-balance-checker
# OR
yarn add eth-balance-checker

Contract

The main contract is in contracts/BalanceChecker.sol. Its associated ABI is in abis/BalanceChecker.abi.json. Both of these are included in the NPM package if you want to compile them yourself, or extend them with another contract.

Library

There are separate libraries for web3.js and ethers.js, both with identical APIs. Just import the functions from either eth-balance-checker/lib/web3 or eth-balance-checker/lib/ethers. For all functions, pass "0x0" as the "token" address to get the ether balance of an address.

All functions also take in an optional 4th options parameter, those options are as follows:

interface Options {
  // Choose a custom contract address. Must be provided to run the
  // code on non-mainnet network.
  contractAddress?: string;
}

getAddressBalances

Parameters

• provider: Web3 | Ethers.Provider - The provider to use for the contract call.
• address: string - The address to lookup balances for
• tokens: string[] - Array of token contract addresses. Only supports ERC20 tokens.
• options?: Options - Options for the contract, see above for options.

Returns

Promise<{
  // Ether balance
  "0x0": "100",
  // Token balances
  "0x123...": "500",
  "0x456...": "100000",
  ...
}>

Example

import Web3 from 'web3';
import { getAddressBalances } from 'eth-balance-checker/lib/web3';

const web3 = new Web3(...);
const address = '0x123...';
const tokens = ['0x0', '0x456...'];
getAddressBalances(web3, address, tokens).then(balances => {
  console.log(balances); // { "0x0": "100", "0x456...": "200" }
});

getAddressesBalances

Parameters

• provider: Web3 | Ethers.Provider - The provider to use for the contract call.
• addresses: string[] - Array of addresses to lookup balances for.
• tokens: string[] - Array of token contract addresses. Only supports ERC20 tokens.
• options?: Options - Options for the contract, see above for options.

Returns

Promise<{
  // Address as the key
  "0x123...": {
    // Ether balance
    "0x0": "100",
    // Token balances
    "0x456...": "500",
    "0x789...": "10000",
    ...
  },
  ...
}>

Example

import * as Ethers from 'ethers';
import { getAddressesBalances } from 'eth-balance-checker/lib/ethers';

const ethers = Ethers.getDefaultProvider();
const addresses = ['0x123...', '0x456...'];
const tokens = ['0x0', '0x789...'];
getAddressBalances(ethers, addresses, tokens).then(balances => {
  console.log(balances); // { "0x123...": { "0x0": "100", ... }, ... }
});

Development

Setup

Requires node 8+. Just install packages, then use commands as needed:

npm install
# OR
yarn

Commands

• build:contract - Runs truffle compile on the contract, and extracts ABI.
• build:lib - Runs tsc and outputs js and typedefs to lib/
• build - Runs build:contract then build:lib
• test:contract - Runs truffle test
• test:lib - No tests implemented yet
• test - Runs tst:contract and test:lib

Credits

• Thanks to @henrynguyen5 for adapting @DeltaBalances' smart contract for this
• This library came out of EthSanFrancisco from the Safu Chrome Extension project.