Basic AJAX Request

example.js

var response;

function makeRequest (url) {
    var xmlhttp = new XMLHttpRequest();

    xmlhttp.onreadystatechange = function(){
        if (xmlhttp.readyState == 4 && xmlhttp.status == 200){
            response = xmlhttp.responseText;            
        }
    }
    xmlhttp.open("GET", url, true);
    xmlhttp.send();
}

makeRequest('http://jsonplaceholder.typicode.com/posts/3');
console.log(response);

request.js

var response;

function makeRequest (url) {
    var xmlhttp = new XMLHttpRequest();

    xmlhttp.onreadystatechange = function(){
        if (xmlhttp.readyState == 4 && xmlhttp.status == 200){
            response = xmlhttp.responseText;            
        }
    }
    xmlhttp.open("GET", url, true);
    xmlhttp.send();
}