check balance of a wallet in js
const testnet = 'https://ropsten.infura.io/'; const walletAddress = '0x8690F1feff62008A396B31c2C3f380bD0Ca6d8b8'; const web3 = new Web3(new Web3.providers.HttpProvider(testnet)); var balance = web3.eth.getBalance(walletAddress); //Will give value in. balance = web3.toDecimal(balance);