express 设置跨域

app.use(function (req, res, next) {

    res.header('Access-Control-Allow-Origin', 'http://localhost:8081');

    //允许的header类型

    res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept, Authorization");

    res.header("Access-Control-Allow-Methods","DELETE,PUT,POST,GET,OPTIONS");

    if (req.method.toLowerCase() == 'options')

        res.send(200);  //让options尝试请求快速结束

    else

        next();

});