Basic XHR example

by Financial Modeling Prep

HTML

<input type="button" id="basicXHRButton" value="Try It">

JavaScript

document.getElementById("basicXHRButton").addEventListener("click", function() {
        // Loading the jQuery code
        request = new XMLHttpRequest();
        request.open("GET", "https://fmpcloud.io/api/v3/mutual-fund-holder/AAPL", true);
          request.setRequestHeader('Access-Control-Allow-Headers', '*');
    request.setRequestHeader('Content-type', 'application/ecmascript');
    request.setRequestHeader('Access-Control-Allow-Origin', '*');
        request.send(null);

        request.onreadystatechange = function() {
            if(request.readyState === 4) { // What does this even mean?
                if(request.status === 200) {
                    console.log(request.responseText);
                    console.log(request.responseText)
                }
            }
        }
    });