1、在 mounted 中自动检测浏览器是否安装MetaMask钱包

 mounted () {
    if (window.ethereum) {
      window.ethereum.enable().then((res) => {
        //alert("当前钱包地址："+res[0])
      })
    }else{
      alert("请安装MetaMask钱包")
    }
  }

2、查询钱包余额

let web3 = new Web3(window.web3.currentProvider)
let fromAddress = web3.eth.accounts[0];
web3.eth.getBalance(fromAddress,(err, res) => {
   if (!err) {
       console.log("余额==",res.toNumber()/Math.pow(10,18));
   }
 })

3、查询代币余额

let web3 = new Web3(window.web3.currentProvider)
let fromAddress = web3.eth.accounts[0];
let ethContract = web3.eth.contract("代币合约Abi")
let functionInstance = ethContract.at("代币合约地址")
functionInstance.balanceOf(fromAddress,(err, res) => {
   if (!err) {
       //代币精度根据所发行的代币合约精度换算 
       console.log("代币余额==",res.toNumber()/Math.pow(10,18));
   }
})

4、转账

let web3 = new Web3(window.web3.currentProvider)
let fromAddress = web3.eth.accounts[0];
//转账数量
let amount = 1*Math.pow(10,18);
//收款地址
let toAddress = "0x40141cF4756A72DF8D8f81c1E0c2ad403C127b9E";
web3.eth.sendTransaction({
    gas: 21000,
    gasPrice: 5000000000,
    from: fromAddress,
    to: toAddress,
    value: amount
 }, (err, result) => {
     console.log("转账Hash=",result)
 })

5、代币转账

let web3 = new Web3(window.web3.currentProvider)
let ethContract = web3.eth.contract("代币Abi")
let functionInstance = ethContract.at("代币地址")
//当前钱包地址
let fromAddress = web3.eth.accounts[0];
//转账数量
let amount = 100*Math.pow(10,18);
//接收地址
let toAddress = "0x40141cF4756A72DF8D8f81c1E0c2ad403C127b9E";
functionInstance.transfer(toAddress,amount,{
     gas: 21000,
     gasPrice: 5000000000,
     from: fromAddress
 }, (err, result) => {
       console.log("转账Hash:",result)
  })

6、代币授权

let web3 = new Web3(window.web3.currentProvider)
let abiContract = web3.eth.contract("代币合约Abi")
let contractInstance = abiContract.at("代币合约地址")
//当前钱包地址
var fromAddress = web3.eth.accounts[0];
//授权数量
var amount = 1000 * Math.pow(10,18);
contractInstance.approve("授权地址",amount,{
    gas: 80000,
    gasPrice: 1500000000,
    from: fromAddress
}, (err, result) => {
    console.log("交易Hash：",result)
})

7、查询授权数量

let web3 = new Web3(window.web3.currentProvider)
let abiContract = web3.eth.contract("代币合约Abi")
let contractInstance = abiContract.at("代币合约地址")
contractInstance.allowance("授权的用户钱包地址","授权的地址",(err, res) => {
    if (!err) {
        console.log("授权数量==",res.toNumber());
    }
}) 

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