Ajax without jQuery for beginners

Before years I was writing all the code by my own, without additional libraries (including jQuery). For beginner developer it’s a good strategy. When you use $.ajax it’s all that easy: $.ajax({ url: "any/url/for/the/request", type: "get", success: function(data){ alert(data); } }); But you can’t get the main idea. Many developers don’t have an idea how to write this without a library. In their opinion AJAX without library a hard, near impossible task.