Javascript 从私有以太坊区块链在浏览器中实时更新用户余额_Javascript_Node.js_Express_Ethereum_Web3

Javascript 从私有以太坊区块链在浏览器中实时更新用户余额

javascript node.js express ethereum

Javascript 从私有以太坊区块链在浏览器中实时更新用户余额,javascript,node.js,express,ethereum,web3,Javascript,Node.js,Express,Ethereum,Web3,问题我希望有一个网站能够通过私有以太坊区块链实时更新用户的财富当前解决方案（已损坏）我打开了一个websocket到一个正在挖掘的私有以太坊区块链，我想更新前端的coinbase余额。我的代码如下： const express = require("express"); const Web3 = require("web3"); var app = express(); app.get("/", (req, res) => res.send("hello w

问题

我希望有一个网站能够通过私有以太坊区块链实时更新用户的财富

当前解决方案（已损坏）

我打开了一个websocket到一个正在挖掘的私有以太坊区块链，我想更新前端的coinbase余额。我的代码如下：

const express    = require("express");
const Web3       = require("web3");


var app  = express();

app.get("/", (req, res) => res.send("hello world from ping ether application"));
app.get("/ping-ether", function(req, res){


    var web3 = new Web3(new Web3.providers.WebsocketProvider('ws://localhost:8546'));

    var event_newBlockHeaders = web3.eth.subscribe("newBlockHeaders", function(err, result){

        if (err){ 

            console.log(err) 

        } else {

            let acctPromise = web3.eth.getAccounts().then(function(accts){

                let balance = web3.eth.getBalance(accts[0]).then(function(bal){

                    console.log("user: ", accts[0]);
                    console.log("balance: ", bal);

                    res.end("new balance for user: " + bal)

                });

            });
        }

    });


});


// run the server
app.listen(3000, () => console.log("web app listening on port 3000"));

很明显，这并不是在前端实时更新，即使最内部的回调不断触发，我可以在控制台上确认这一点。我想要三样东西：

我应该如何更改此代码，以便前端具有coinbase余额的实时行情器

一般来说，这段代码带有嵌套承诺的味道。如何重构它，使我不必每次导航到

/ping以太时都建立websocket连接


欢迎提出任何其他建议。我对node.js非常陌生
未经测试，但类似的方法应该有效：
const express    = require("express");
const Web3       = require("web3");

var app  = express();
var web3 = new Web3(new Web3.providers.WebsocketProvider('ws://localhost:8546'));
var balance = -1;

web3.eth.getAccounts().then(accounts => {
  return web3.eth.subscribe("newBlockHeaders", (err, result) => {
    if (err) {
      console.log(err);
    } else {
      web3.eth.getBalance(accounts[0]).then(bal => {
        console.log("user: ", accounts[0]);
        console.log("balance: ", bal);
        balance = bal;
      });
    }
  })
}).then(() => {
  app.listen(3000, () => console.log("web app listening on port 3000"));
});

app.get("/", (req, res) => res.send("hello world from ping ether application"));
app.get("/ping-ether", function (req, res) {
  res.end("new balance for user: " + balance);
});

主要思想是设置websocket连接和订阅一次，然后用当前余额响应传入的web请求。我还试图通过返回订阅承诺来清理嵌套的承诺。
更新：我最终使用了websocket，以下是解决方案：
import * as Web3     from 'web3'     ; 
import * as express  from 'express'  ;
import * as socketIO from 'socket.io';
import * as http      from 'http'    ;


const CLIENT_PATH = 'path/to/directory'

var app    = express();
var server = http.Server(app);
var io     = socketIO(server);
var web3   = new Web3(new Web3.providers.WebsocketProvider('ws://localhost:8546'));

app.get('/', (req,res) => {
    res.sendFile(CLIENT_PATH + '/index.html');
});


web3.eth.getAccounts().then(accounts => {

    display_account(accounts)
})

function display_account(accounts){

    var user_0 = accounts[0]

    web3.eth.subscribe('newBlockHeaders', (err, ret) => {

        if (err){ 

            console.log("error: ", err)

        } else {

            web3.eth.getBalance(user_0).then(bal => {

                var msg = 'Balance for user ' + user_0 + ' is ' + bal  
                io.emit('message-1', msg)
                console.log('emitted message: ', msg)

            })
        }

    })

}


// use this instead of app.listen
server.listen(3000, () => {

    console.log('listening on 3000')

});

这是index.html
<html>
<head></head>

<body>
  <div id="message"></div>

  <script src="/socket.io/socket.io.js"></script>
  <script>

    var socket = io();

    socket.on('message-1', function(msg){
      console.log(msg);
      document.getElementById("message").innerHTML = msg;
    });

  </script>
</body>
</html>


var socket=io（）；
socket.on（'message-1'，函数（msg）{
控制台日志（msg）；
document.getElementById（“message”）.innerHTML=msg；
});