如果我在本地运行Node.js服务器，我究竟应该在http请求中使用什么作为参数'url'？

Question

I'm trying to make a simple http request to my local server (running by Node.js). How my needed url should looks like?

I'm trying to make my website behaves in a next way: After button click the script is run. Script forms http request and sends it to my Node server, which I run locally on my computer with command line. The Node server handles http request, fetches data from my mongodb database and responds with this data to my script. Finally, the script must output the data as a content on a webpage. The problem is that I get this error in a browser console:

'Access to XMLHttpRequest at 'file:///C:/.../serverSide.js' from origin 'null' has been blocked by CORS policy: Cross origin requests are only supported for protocol schemes: http, data, chrome, chrome-extension, https.'

I guess it is because of invalid url, which I used as an argument in my http request. All of my files (html, script and node serverside) are in the same folder. I have already used following url values: 'serverSide.js' , 'http://localhost:8080/' , 'localhost:8080' and all of them caused an error which is above. So, what should I use as url ?

my script:

function textOutput() {

    let xhttp = new XMLHttpRequest();

    xhttp.onreadystatechange = function () {
        if ( this.readyState == 4 && this.status == 200 ) {
            document.getElementById('questionText').innerHTML = 
this.responseText
        }
    };

    xhttp.open('GET', 'serverSide.js', true);
    xhttp.send();
};

here is part of my serverside which is handling the request:

...
http.createServer(function (req, res) {
    ukrlitquestions.findOne({id: randomId(1, docsAmount)}, 'text', 
function(err, result) {
        if (err) console.log(err);
        let quesText = result.text;
        res.write(quesText);
        console.log(quesText);
        res.end();
    });
}).listen(8080);
...

Answer 1

You'll need to point to the correct domain. Something like http://localhost:3000/server-side.js

Answer 2

What you are seeing is a CORS error. https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS

The web browser sends an OPTION request before sending the real request. The Url should be something like http://localhost:8080/server-side.js

Try adding the following to the server side:

 if (req.method === "OPTIONS") {
    res.sendStatus(200);
  }

Answer 3

打开http.open（'GET'，' http：// localhost：8080 / serverSide.js '，true）

Answer 4

You need to allow CORS from your server. You can achieve that by adding this.

...
http.createServer(function (req, res) {
  res.setHeader('Access-Control-Allow-Origin, '*')
  ...