ajaxcall.js

function get(url, data, callback){
  if(typeof data === "function") {
    callback = data;
    data = {};
  }

  var xhr = new XMLHttpRequest();
  xhr.open("GET", url, true);
  xhr.setRequestHeader("Content-Type","application/json");
  xhr.send(JSON.stringify(data));
  xhr.onreadystatechange = function() {
    callback(xhr.responseText, xhr.statusCode);
  }

}

get("exmaple.com", function(data){
  console.log(data);
})