跨域问题

https://www.cnblogs.com/pass245939319/p/9040802.html

使用cors：

app.use("*", function (req, res, next) {

    res.header('Access-Control-Allow-Origin', '*');

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

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

    if (req.method === 'OPTIONS') {

        res.send(200)

    } else {

        next()

    }

});