@0xcert/ethereum-utils

General Ethereum utility module with helper functions for the Ethereum blockchain.

The 0xcert Framework is a free and open-source JavaScript library that provides tools for building powerful decentralized applications. Please refer to the official documentation for more details.

This module is one of the bricks of the 0xcert Framework. It's written with TypeScript and it's actively maintained. The source code is available on GitHub where you can also find our issue tracker.

Ethereum Utilities

This module wraps several useful Ethereum functions which will be useful through the 0xcert Framework. Currently supported are these functions and classes from ethers.js:

ABI coder

This converts value to and from the packed Ethereum ABI encoding.

• encodeParameters(types: any, values: Array<any>): string
• decodeParameters(types: any, data: any): any

Encoding example:

import { decodeParameters, encodeParameters } from '0xcert/ethereum-utils/abi';

const types = ['tuple(uint256, uint256[])'];
const values = [[ 42, [ 45 ] ]];
const encodedValues = encodeParameters(types, values);

Decoding example:

import { decodeParameters, encodeParameters } from '0xcert/ethereum-utils/abi';

const types = ['tuple(uint256, uint256[])'];
const encoded = '0x' +
  '0000000000000000000000000000000000000000000000000000000000000020' +
  '000000000000000000000000000000000000000000000000000000000000002a' +
  '0000000000000000000000000000000000000000000000000000000000000040' +
  '0000000000000000000000000000000000000000000000000000000000000001' +
  '000000000000000000000000000000000000000000000000000000000000002d';
const values = decodeParameters(types, values);

Big umbers

Here is a basic example adapted from the ethers.js documentation.

import { bigNumberify } from '0xcert/ethereum-utils/big-number';

let gasPriceWei = bigNumberify("20902747399");
let gasLimit = bigNumberify(3000000);

let maxCostWei = gasPriceWei.mul(gasLimit)
console.log("Max Cost: " + maxCostWei.toString());
// "Max Cost: 62708242197000000"

console.log("Number: " + maxCostWei.toNumber());
// throws an Error, the value is too large for JavaScript to handle safely

Address normalization

The ethers.js address normalization function implements EIP-55 Mixed-case checksum address encoding.

import { getAddress } from '0xcert/ethereum-utils/normalize-address';

let zxcTokenAddress = '0x83e2be8d114f9661221384b3a50d24b96a5653f5';
let zxcTokenAddressNormalized = normalizeAddress(zxcToenAddress);
// 0x83e2BE8d114F9661221384B3a50d24B96a5653F5