雲禾遗密：Web3js调用智能合约查看某账户ERC20代币数量

知识点：

1、.then()

js中then（）的用法_spider_man-CSDN博客_js then

2、let和var

var和let的区别 - 知乎

3、箭头函数

js中 => 的含义_小白菜的专栏-CSDN博客_js中=>

4、wei到ether转换方法web3.js 1.0中文手册 / web3.utils.fromWei - 从wei转换到其他以太单位 - 汇智网

5、总参考

web3.js（三）查询智能合约币数量（erc20）_侞婼冇罪-CSDN博客

正题：

1、安装nodejs，并安装web3.js包

2、复制下方代码保存xxxx.js

3、node xxxx.js

// 实例化web3 并指定http链接到主网
const Web3 = require("web3")
const web3 = new Web3("https://mainnet.infura.io/v3/c33e4b53375843259ec8bb7fef608456")

// 设置合约abi
let token_abi = [{ "constant": true, "inputs": [], "name": "name", "outputs": [{ "name": "", "type": "string" }], "payable": false, "stateMutability": "view", "type": "function" }, { "constant": false, "inputs": [{ "name": "_spender", "type": "address" }, { "name": "_value", "type": "uint256" }], "name": "approve", "outputs": [{ "name": "", "type": "bool" }], "payable": false, "stateMutability": "nonpayable", "type": "function" }, { "constant": true, "inputs": [], "name": "totalSupply", "outputs": [{ "name": "", "type": "uint256" }], "payable": false, "stateMutability": "view", "type": "function" }, { "constant": false, "inputs": [{ "name": "_from", "type": "address" }, { "name": "_to", "type": "address" }, { "name": "_value", "type": "uint256" }], "name": "transferFrom", "outputs": [{ "name": "", "type": "bool" }], "payable": false, "stateMutability": "nonpayable", "type": "function" }, { "constant": true, "inputs": [], "name": "INITIAL_SUPPLY", "outputs": [{ "name": "", "type": "uint256" }], "payable": false, "stateMutability": "view", "type": "function" }, { "constant": true, "inputs": [], "name": "decimals", "outputs": [{ "name": "", "type": "uint256" }], "payable": false, "stateMutability": "view", "type": "function" }, { "constant": false, "inputs": [], "name": "unpause", "outputs": [], "payable": false, "stateMutability": "nonpayable", "type": "function" }, { "constant": true, "inputs": [], "name": "paused", "outputs": [{ "name": "", "type": "bool" }], "payable": false, "stateMutability": "view", "type": "function" }, { "constant": false, "inputs": [{ "name": "_spender", "type": "address" }, { "name": "_subtractedValue", "type": "uint256" }], "name": "decreaseApproval", "outputs": [{ "name": "success", "type": "bool" }], "payable": false, "stateMutability": "nonpayable", "type": "function" }, { "constant": true, "inputs": [{ "name": "_owner", "type": "address" }], "name": "balanceOf", "outputs": [{ "name": "balance", "type": "uint256" }], "payable": false, "stateMutability": "view", "type": "function" }, { "constant": false, "inputs": [], "name": "pause", "outputs": [], "payable": false, "stateMutability": "nonpayable", "type": "function" }, { "constant": true, "inputs": [], "name": "owner", "outputs": [{ "name": "", "type": "address" }], "payable": false, "stateMutability": "view", "type": "function" }, { "constant": true, "inputs": [], "name": "symbol", "outputs": [{ "name": "", "type": "string" }], "payable": false, "stateMutability": "view", "type": "function" }, { "constant": false, "inputs": [{ "name": "_to", "type": "address" }, { "name": "_value", "type": "uint256" }], "name": "transfer", "outputs": [{ "name": "", "type": "bool" }], "payable": false, "stateMutability": "nonpayable", "type": "function" }, { "constant": false, "inputs": [{ "name": "_spender", "type": "address" }, { "name": "_addedValue", "type": "uint256" }], "name": "increaseApproval", "outputs": [{ "name": "success", "type": "bool" }], "payable": false, "stateMutability": "nonpayable", "type": "function" }, { "constant": true, "inputs": [{ "name": "_owner", "type": "address" }, { "name": "_spender", "type": "address" }], "name": "allowance", "outputs": [{ "name": "", "type": "uint256" }], "payable": false, "stateMutability": "view", "type": "function" }, { "constant": false, "inputs": [{ "name": "newOwner", "type": "address" }], "name": "transferOwnership", "outputs": [], "payable": false, "stateMutability": "nonpayable", "type": "function" }, { "inputs": [], "payable": false, "stateMutability": "nonpayable", "type": "constructor" }, { "anonymous": false, "inputs": [], "name": "Pause", "type": "event" }, { "anonymous": false, "inputs": [], "name": "Unpause", "type": "event" }, { "anonymous": false, "inputs": [{ "indexed": true, "name": "previousOwner", "type": "address" }, { "indexed": true, "name": "newOwner", "type": "address" }], "name": "OwnershipTransferred", "type": "event" }, { "anonymous": false, "inputs": [{ "indexed": true, "name": "owner", "type": "address" }, { "indexed": true, "name": "spender", "type": "address" }, { "indexed": false, "name": "value", "type": "uint256" }], "name": "Approval", "type": "event" }, { "anonymous": false, "inputs": [{ "indexed": true, "name": "from", "type": "address" }, { "indexed": true, "name": "to", "type": "address" }, { "indexed": false, "name": "value", "type": "uint256" }], "name": "Transfer", "type": "event" }]

// 设置合约地址
let contract_address = "0xf85feea2fdd81d51177f6b8f35f0e6734ce45f5f"

// 创建一个新的合约实例
mycontract = new web3.eth.Contract(token_abi, contract_address)

// 调用合约里面的balanceOf方法看代币数量
// 设置看这个人的
let user_address = "0x46705dfff24256421a05d056c29e81bdc09723b8"

// 调用合约方法
haha = mycontract.methods.balanceOf(user_address).call().then(function (result) {
    console.log(web3.utils.fromWei(result, 'ether'));
})