nodejs 实现跨域

1、nodejs

let http = require('http');

http.createServer((req,res) => {

　　　res.setHeader("Access-Control-Allow-Origin", "http://localhost:7000"); // 设置可访问的源

    res.setHeader("Access-Control-Allow-Headers", "Content-Type"); 
    res.setHeader("content-type", "application/json")
    res.end(JSON.stringify({
        data: {
            msg: 'hello world!'
        },
        status: 'success'
    }))
}).listen(8000)

js:

$.ajax({
            type: 'post',
            url: 'http://localhost:8000',
            headers: {
            'Content-type': "application/json"
             },
            success: function (res) {
                console.log('success')
            },
            error(err) {
                console.error(err)
            }
        })

2、nodejs express

var express = require('express');
var app = express();
var cors = require('cors');
app.use(cors());
//设置跨域访问
app.all('*', function(req, res, next) {
res.header("Access-Control-Allow-Origin", "http://localhost:7000");
res.header("Access-Control-Allow-Headers", "Content-Type,Access-Token");
res.header("Access-Control-Allow-Methods","PUT,POST,GET,DELETE,OPTIONS");
res.header("X-Powered-By",' 3.2.1');
res.header("Content-Type", "application/json;charset=utf-8");
res.end(JSON.stringify({
    data: 'hello world!'
}))
});
app.listen(8000);