|
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<script src="../js/web3.min.js"></script>
</head>
<body>
<h1>Get ERC20-Token Balance</h1>
<h2>Contract Address</h2>
<input type="text" id="contract-address" size="80" oninput="onAddressChange()"></input>
<p>ex> 0xcd45a142d109bbc8b22ff6028614027d1db4e32f</p>
<h2>Wallet Address</h2>
<input type="text" id="wallet-address" size="80" oninput="onAddressChange()"></input>
<p>ex> 0x528018c88448f67d2b618a43546cf7e0b026857e</p>
<h2>Result</h2>
<span id="result"></span>
<script>
function getERC20TokenBalance(tokenAddress, walletAddress, callback) {
let minABI = [
{
"constant":true,
"inputs":[{"name":"_owner","type":"address"}],
"name":"balanceOf",
"outputs":[{"name":"balance","type":"uint256"}],
"type":"function"
},
// decimals
{
"constant":true,
"inputs":[],
"name":"decimals",
"outputs":[{"name":"","type":"uint8"}],
"type":"function"
}
];
let contract = web3.eth.contract(minABI).at(tokenAddress);
contract.balanceOf(walletAddress, (error, balance) => {
contract.decimals((error, decimals) => {
balance = balance.div(10**decimals);
console.log(balance.toString());
callback(balance);
});
});
}
function onAddressChange(e) {
let tokenAddress = document.getElementById('contract-address').value;
let walletAddress = document.getElementById('wallet-address').value;
if(tokenAddress != "" && walletAddress != "") {
getERC20TokenBalance(tokenAddress, walletAddress, (balance) => {
document.getElementById('result').innerText = balance.toString();
});
}
}
window.onload = function() {
if (typeof web3 !== 'undefined') {
web3 = new Web3(web3.currentProvider);
} else {
web3 = new Web3(new Web3.providers.HttpProvider("https://ropsten.infura.io/v3/f76f49a440bf4303ab6d2c1aa21c7537"));
}
console.log(web3.version);
}
</script>
<p>ex> https://mainnet.infura.io</p>
</body>
</html> | 
