NodeJs express 设置跨域请求头

var express = require('express');
var app = express();

app.all('*', function(req, res, next) {
    res.header("Access-Control-Allow-Origin", "*")
    res.header("Access-Control-Allow-Headers", "X-Requested-With")
    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")
    next()
});

// 根据情况设置，不需要全部都设置。