先说明，我并不知道出现坑的原因是什么。我只是按照别人的写法就连上了。我的处境是这样的我的前台是用了 vue 全家桶，启动了一个 9527 端口。而我的后台是用 nodeJS，启动了 8081 端口。很明显，这种情况就出现了头疼的跨域。贴出我的代码，如下server.js（后台）
var app = express();
var server = require('http').createServer(app);
var io = require('socket.io')(server);
io.sockets.on('connection', (socket) => {
console.log('123')
});
var app = express();
var server = require('http').createServer(app);
var io = require('socket.io')(server);
io.sockets.on('connection', (socket) => {
console.log('123')
});main.js（前台）
import VueSocketio from 'vue-socket.io'
import socketio from 'socket.io-client'
Vue.use(VueSocketio, socketio('http://localhost:8081'), store)
import VueSocketio from 'vue-socket.io'
import socketio from 'socket.io-client'
Vue.use(VueSocketio, socketio('http://localhost:8081'), store)然后根据网上的写法，我在后端对跨域进行了处理
app.all('*',function (req, res, next) {
res.header('Access-Control-Allow-Origin', 'http://localhost:9527');
res.header('Access-Control-Allow-Headers', 'X-Token, Content-Type, Content-Length, Authorization, Accept, X-Requested-With , yourHeaderFeild');
res.header('Access-Control-Allow-Methods', 'PUT, POST, GET, DELETE, OPTIONS');
if (req.method == 'OPTIONS') {
res.send(200); /*让options请求快速返回*/
}
else {
next();
}
});
app.all('*',function (req, res, next) {
res.header('Access-Control-Allow-Origin', 'http://localhost:9527');
res.header('Access-Control-Allow-Headers', 'X-Token, Content-Type, Content-Length, Authorization, Accept, X-Requested-With , yourHeaderFeild');
res.header('Access-Control-Allow-Methods', 'PUT, POST, GET, DELETE, OPTIONS');
if (req.method == 'OPTIONS') {
res.send(200); /*让options请求快速返回*/
}
else {
next();
}
});满心欢喜的重启前台看下有没有脸上。结果出现了一下错误
Failed to load http://localhost:8081/socket.io/?EIO=3&transport=polling&t=MAqqfjf: The value of the 'Access-Control-Allow-Credentials' header in the response is '' which must be 'true' when the request's credentials mode is 'include'. Origin 'http://localhost:9527' is therefore not allowed access. The credentials mode of requests initiated by the XMLHttpRequest is controlled by the withCredentials attribute.
Failed to load http://localhost:8081/socket.io/?EIO=3&transport=polling&t=MAqqfjf: The value of the 'Access-Control-Allow-Credentials' header in the response is '' which must be 'true' when the request's credentials mode is 'include'. Origin 'http://localhost:9527' is therefore not allowed access. The credentials mode of requests initiated by the XMLHttpRequest is controlled by the withCredentials attribute.这个错误。。我看得出是是 “Access-Control-Allow-Credentials” 的问题。所以我又改了后台的跨域代码
app.all('*',function (req, res, next) {
res.header('Access-Control-Allow-Origin', 'http://localhost:9527');
res.header('Access-Control-Allow-Headers', 'X-Token, Content-Type, Content-Length, Authorization, Accept, X-Requested-With , yourHeaderFeild');
res.header('Access-Control-Allow-Methods', 'PUT, POST, GET, DELETE, OPTIONS');
res.header('Access-Control-Allow-Credentials','true'); // 新增
if (req.method == 'OPTIONS') {
res.send(200); /*让options请求快速返回*/
}
else {
next();
}
});
app.all('*',function (req, res, next) {
res.header('Access-Control-Allow-Origin', 'http://localhost:9527');
res.header('Access-Control-Allow-Headers', 'X-Token, Content-Type, Content-Length, Authorization, Accept, X-Requested-With , yourHeaderFeild');
res.header('Access-Control-Allow-Methods', 'PUT, POST, GET, DELETE, OPTIONS');
res.header('Access-Control-Allow-Credentials','true'); // 新增
if (req.method == 'OPTIONS') {
res.send(200); /*让options请求快速返回*/
}
else {
next();
}
});更改过后，我又满心欢喜的跑去前台，一看结果就一直报错：
GET http://localhost:8081/socket.io/?EIO=3&transport=polling&t=MAqp7zN 404 (Not Found)
GET http://localhost:8081/socket.io/?EIO=3&transport=polling&t=MAqp7zN 404 (Not Found)
GET http://localhost:8081/socket.io/?EIO=3&transport=polling&t=MAqp7zN 404 (Not Found)GET http://localhost:8081/socket.io/?EIO=3&transport=polling&t=MAqp7zN 404 (Not Found)报错了这个是 404 。百度了很久， 各种关键字都搞不了。最后去 google 了。结果让我找到了答案：看了上面这个答案，我翻查了一下，正好我也是用 express4 的。所以我就按照他的说法去改。结果如下。正确的写法后端
var server = app.listen(8081);
var io = require('socket.io').listen(server);
io.sockets.on('connection', (socket) => {
console.log('123')
});
var server = app.listen(8081);
var io = require('socket.io').listen(server);
io.sockets.on('connection', (socket) => {
console.log('123')
});前端的写法不变。思考点思考点思考点虽然我不知道背后发生了什么事（因为是赶项目，赶鸭子上架写 node 和 vue 的，本人是 Java 开发），但是我还是觉得有几个点要注意的：1、关于 Express 4 和 其他版本中，socketio 的写法不同，少了一个 http 模块。所以我认为是出现这种情况的主要原因2、注意跨域的写法。四行代码，最好能够保存下来。3、如果是本地测试的，需要注意 IP 问题。如果是 localhost 的，请前后端一直；如果是 127.0.0.1，请前后端一致。以上这篇浅谈vue websocket nodeJS 进行实时通信踩到的坑就是小编分享给大家的全部内容了，希望能给大家一个参考。