**AJAX** is a set of web development techniques that use many web technologies on the client-side to create asynchronous web applications.  
- With AJAX, web applications can asynchronously send and retrieve data from a server without interfering with the existing page’s display and behavior. 
- AJAX is not a programming language, and it requires a built-in browser with an 
XMLHttpRequest object that requests data from the server.
 - AJAX uses JavaScript and HTML DOM to display data.

# AJAX success

Whenever an AJAX request successfully completes, `jQuery` triggers the `ajaxSuccess` event. All handlers that have been registered with the `.ajaxSuccess()` method are executed at this time. It is essentially a function to be run when the request succeeds.

```
success(result,status,xhr)	
```
# Example
To use `.ajaxSuccess()` a demo or test file is required. 

For example, in the output below, we want to change the heading. When we click on the button, it will change the output of the document. We will define our relevant content in the test file, `test_file.txt`. Upon success, the content is replaced with the content of our test file. 


```
// test_file.txt
<h2> Hello world </h2>
<p> Today is Monday. </p>
```


<!DOCTYPE html>
<html>
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
<script>
$(document).ready(function(){
  $("button").click(function(){
    $.ajax({url: "test_file.txt", success: function(result){
      $("#div").html(result);
    }});
  });
});
</script>
</head>
<body>

<div id="div"><h2>The button will change this text</h2></div>

<button>Click me</button>

</body>
</html>



codemirror

<html>
 <head>
 </head>
 <body>
   <div id="content"/>
   <h2> Hello world </h2>
   <p> Today is Monday. </p>
 </body>
</html>

What is AJAX success?

AJAX allows asynchronous data exchange between client and server without altering the page. AJAX requests trigger the ajaxSuccess event on completion.