Basic AJAX Methods

AJAX.js

const AJAX = {
	get: function(url,onGet) {
    	var xhttp = new XMLHttpRequest();
        xhttp.onreadystatechange = function() {
          if (this.readyState == 4 && this.status == 200) {
            onGet(this.responseText);
          }
        };
        xhttp.open("GET", url, true);
        xhttp.send();
        
    },
    post: function(url,onGet,header,data) {
    	var xhttp = new XMLHttpRequest();
        xhttp.onreadystatechange = function() {
          if (this.readyState == 4 && this.status == 200) {
            onGet(this.responseText);
          }
        };
        xhttp.open("GET", url, true);
        if (typeof header == "string") {
            xhttp.setRequestHeader(header);
        } else if (Array.isArray(header)) {
            for (var i = 0; i < header.length; i++) {
                xhttp.setRequestHeader(header[i]);
            }
        }
        xhttp.send(data?data:null);
    }
};