Cross-domain (2) cors

html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>cors例子</title>
</head>
<body>
<script>
   var xmlhttp;
    if (window.XMLHttpRequest)
    {
        //  IE7 +, Firefox, Chrome, Opera , Safari browser executing the code 
        XMLHTTP = new new the XMLHttpRequest (); 
    } 
    the else 
    { 
        // IE6, IE5 browser executing code 
        XMLHTTP = new new the ActiveXObject ( " Microsoft.XMLHTTP " ); 
    } 
    xmlhttp.onreadystatechange = function () 
    { 
        IF (xmlHttp.readyState == . 4 && xmlhttp.status == 200 is ) 
        { 
            the console.log (XMLHTTP) 
        } 
    } 
    xmlhttp.open ( " the GET " , "http://localhost:3000/get",true);
    xmlhttp.send();

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

We create a ajax request interface port 3000

Backend port 4000

server.js

const express = require('express');
const app = express();
app.get('/get',function(req,res) {
       res.end('跨域处理')
})
app.listen(3000, () => console.log('The server is starting at port 3000'));

Generate cross-domain:

Add cross-domain process:

app.all ( '*', function (REQ, RES, Next) { 
      res.header ( 'Access-Control-the Allow-Origin', '*'); 
      // the Allow-Access-Control-Headers, according to the browser F12 of view, the corresponding line paste here 
      res.header ( 'Access-Control-the Allow-Headers', 'the Type-the Content'); 
      res.header ( 'Access-Control-the Allow-Methods', '*') ; 
      res.header ( 'the Content-the Type', 'file application / JSON; charset = UTF-. 8'); 
      Next (); 
    });

　　effect:

Output; cross-domain processing

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Cross-domain (2) cors

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