NodeJS+Express模块的跨域访问控制问题

在一个项目上想用NodeJS,所以边学边练。第一个遇到的问题就是跨域访问控制问题。很多初学者会遇到同样问题。

##问题
在前端的JS(http://localhost/xxx)中ajax访问后端RestAPI(http://localhost:3000/….)时(Chrome)报错:

XMLHttpRequest cannot load http://localhost:3000/auth/xxx/xxx. Origin http://localhost is not allowed by Access-Control-Allow-Origin.

##方案
解决代码如下:
var express = require(‘express’);
var app = express();
//设置跨域访问
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();
});

app.get('/auth/:id/:password', function(req, res) {
    res.send({id:req.params.id, name: req.params.password});
});

app.listen(3000);
console.log('Listening on port 3000...');
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