html5 - EventSource报错-PHP中文网问答

错误

Error: Can't set headers after they are sent.

at ServerResponse.OutgoingMessage.setHeader (_http_outgoing.js:357:11)
at ServerResponse.header (D:\node\javascript-demo\node_modules\express\lib\response.js:730:10)
at ServerResponse.send (D:\node\javascript-demo\node_modules\express\lib\response.js:170:12)
at Timeout.setInterval [as _onTimeout] (D:\node\javascript-demo\routes\eventsource\eventsource.js:8:8)
at ontimeout (timers.js:384:18)
at tryOnTimeout (timers.js:244:5)
at Timer.listOnTimeout (timers.js:214:5) Program node --debug ./bin/www exited with code 1

  
const express = require('express');
const router = express.Router();

router.get('/connect',function(req,resp,next){
    resp.append('Content-Type','text/event-stream');
    console.log(req.method);
    setInterval((data)=>{
        resp.send('hello!');
    },1000,'hello');
});


router.get('/html',(req,resp,next)=>{
    resp.render('./eventsource/msgsend_recevie.html');
});module.exports=router;

<!DOCTYPE html>
<html lang="en">
<head>
    <title>EventSource消息发送</title>
    <style type="text/css">
        *{
            margin:0 auto;
            padding:0;
        }

        p{
            width:440px;
            height:450px;
            border:2px solid;
            margin-top:100px;
        }
</style>
</head>
<body>
    <p>
        <textarea  id="msg_recevie" rows="30" cols="60"></textarea>
    </p>

    <script>
        //使用eventsource发送信息
        var eventSource = new EventSource('/msg_send/connect');
        eventSource.onmessage=function(e){
            var tx=document.getElementsByTagName('textarea')[0];
            tx.value=e.data;
        };

    </script>
</body>    

</html>

const express = require('express'); const router = express.Router(); router.get('/connect',function(req,resp,next){ resp.writeHead(200,{ "Content-Type":"text/event-stream", "Cache-Control":"no-cache", "Connection":"keep-alive" }); setInterval(function(){ resp.write("data:"+Date.now()+"\n\n"); },1000); }); router.get('/html',(req,resp,next)=>{ resp.render('./eventsource/msgsend_recevie.html'); }); module.exports=router;

问题

在express的response已经send后，response不允许再进行header等一系列的操作，setintval是一个定时器，你的逻辑方式没有正确。
你的setintval第一次已经把响应推送出去了，那么后面这个响应已经不能继续操作了，由于http是单向非双向的，所以第二次是无效的操作

问题

解决方案