base requestAjax function

baseAjax.js

function requestAJAX(url, callback) {
    var xhr = new XMLHttpRequest();
    xhr.onreadystatechange = function () {
        if (xhr.readyState == 4 && xhr.status == 200) {
            callback(JSON.parse(xhr.responseText))
        }
    }
    xhr.open('GET', url, true)
    xhr.send()
}