Wei.js and bignumber.js

wei-and-bn.js

import { ethers } from 'ethers';

// import
import BigNumber from 'bignumber.js';
import Wei, { wei } from '@synthetixio/wei';

// construction (string)
let bigNum = new BigNumber('100000000000000000');
let weiNum = wei('1');

// construction (number)
bigNum = new BigNumber(ethers.utils.formatEther(1).toString(), 10);
weiNum = wei(1);

// construction (Ethers.BigNumber)
const ethersBigNum = ethers.utils.parseEther('1');

bigNum = new BigNumber(ethersBigNum.toString());
weiNum = wei(ethersBigNum) // imported as-is (unscaled)

// construction (unscaled BigNumber)
let unscaledBigNum = new BigNumber(123);
let unscaledWeiNum = wei(123, 0);

bigNum = new BigNumber(ethersBigNum.toString());
weiNum = wei(ethersBigNum);

// formatted print
console.log(bigNum.dividedBy(bigNum).precision(2).toString());
console.log(weiNum.toString(2));

// addition/subtraction
bigNum = bigNum.plus(bigNum);
weiNum = weiNum.add(weiNum);
// tip: weiNum = weiNum.plus(1) also works too!

// multiplication/division
bigNum = bigNum.multipliedBy(bigNum).dividedBy(ethers.utils.formatEther(1).toString());
weiNum = weiNum.mul(weiNum);

// conversion to ethers.BigNumber
const bnEthersBignum = ethers.BigNumber.from(bigNum.toString());
const weiEthersBigNum = weiNum.toBN();

// handling invalid input
bigNum = new BigNumber('bad input'); // = NaN
try {
	weiNum = wei('bad input'); // exception
} catch (err) {
	// handle gracefully
}