const APIKEY = 'YOUR API KEY';
const baseURL = 'https://api.covalenthq.com/v1'
const klaytnChainId = '8217'
const demoAddress = '0xFEC4f9D5B322Aa834056E85946A32c35A3f5aDD8'
async function getWalletBalance(chainId, address) {
const url = new URL(`${baseURL}/${chainId}/address/${address}/balances_v2/?key=${APIKEY}`);
const response = await fetch(url);
const result = await response.json();
const data = result.data;
// Example address request
getWalletBalance(klaytnChainId, demoAddress);