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();
});
var questions=[
{
data:213,
num:444,
age:12
},
{
data:456,
num:678,
age:13
}];
//写个接口123
app.get('/123',function(req,res){
res.status(200),
res.json(questions)
});
//配置服务端口
var server = app.listen(3000, function () {
var host = server.address().address;
 var port = server.address().port;
 console.log('Example app listening at http://%s:%s', host, port);
})

npm install express --save

$.ajax({
type:'get',
url:'http://localhost:3000/123',
success:function(data){
console.log(data);
},
error:function(){
console.log('error');
}
})