convert LoadVars & sendAndLoad from actionscript to javascript

Question

I am a beginning programmer and trying to convert a program in Actionscript to javascript.

So far I could do all the conversions I needed, but I am stuck on the following code below.

I understand that the variables fileName & test ID are sent to the script which is located at the url interfaceUrl + "operation=" + Test and the answer is stored back in lvReply.

Which code/function I would need in JavaScript to do the same.

I am looking at XMLHttpRequest but do not know if this is the right way to move forward. Any help in pointing me to the right direction would be appreciated.

var lv:LoadVars = new LoadVars();

    lv.fileName = fileName;
    lv.lpTestId = testId;

var lvReply:LoadVars = new LoadVars();
        
lv.sendAndLoad(interfaceUrl + "operation=" + Test, lvReply, "POST");

Answer 1

LoadVars just loads name / value pairs from the server, in the form of:

someText=testing&myVariable=123

For JavaScript, you can use:

XHR:
https://developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequest

to load the data, and then:

URLSearchParams to parse them:
https://developer.mozilla.org/en-US/docs/Web/API/URLSearchParams

Here is some pseudo code to demonstrate:

let xhr = new XMLHttpRequest();

//load data, sending params to server via query string
xhr.open('GET', 'http://example.com/data?args1=boof&arg2=banana'); 

xhr.onload = function() {
  if (xhr.status != 200) { 
    //check status code to see what happened
  } else {

    //data sent from server in the form of foo=bar&biff=bam
    let data = xhr.response;

    let params = URLSearchParams(data);

    let foo = params.get(foo);
    console.log(foo); // prints bar
  }
};

xhr.onerror = function(err) {
  //something went wrong
};

xhr.send();

A better solution would be just to send JSON from the server and parse it with JSON.parse()

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/parse

Note, in the example above, it is also sending data to the server. You can also do that using XHR (either via GET or POST).