How to create the XMLHttpRequest object and what are the uses of XMLHttpRequest object in AJAX?

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Ethan Karla asked 29 days ago in programming by Ethan Karla

How to create the XMLHttpRequest object and what are the uses of XMLHttpRequest object in AJAX?

1 Answer

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Ravi Vishwakarma answered 28 days ago by Ravi Vishwakarma

An object of XMLHttpRequest is used for Asynchronous Communication between Client and Server.

There are some uses of XMLHttpRequest.
  1. It sends data to the client in the background.
  2. It receives data from the server.
  3. Updates it on the webpage without reloading it.

Create the XMLHttpRequest in Ajax.

Syntax

XML_Http_name = new XMLHttpRequest();

Callback function of XMLHttpRequest in ajax.

Syntax

XML_Http_name.onload = function() {
  // the callback function should contain the code to execute when the response is ready.
}

Send a Request on a server in ajax

    To send a request to a server, you can use the open() and send() methods of the XMLHttpRequest object

XML_Http_name.open(method, url, async, user, psw);
XML_Http_name.send();
method: the request type GET or POST

URL: the file location
async: true (asynchronous) or false (synchronous)
user: optional user name
psw: optional passwordxhttp.open('mwthod', 'ajax_info.txt');

Example 

<!doctype html>

<html lang='en'>
<head>
    <!-- Required meta tags -->
    <meta charset='utf-8'>
    <meta name='viewport' content='width=device-width, initial-scale=1'>
    <!-- Bootstrap CSS -->
    <link href='https://cdn.jsdelivr.net/npm/bootstrap@5.0.2/dist/css/bootstrap.min.css' rel='stylesheet' integrity='sha384-EVSTQN3/azprG1Anm3QDgpJLIm9Nao0Yz1ztcQTwFspd3yD65VohhpuuCOmLASjC' crossorigin='anonymous'>
    <title>Ajax Example</title>
</head>
<body>
    <div class='container'>
        <h1 class='text-center'>Ajax Example </h1>
        <button type='button' onclick='loadDoc()' class='btn btn-primary my-3' >Click me</button>
        <p id='loadAjax'>Click button then call the ajax without reload the page</p>
    </div>
    <script>
        function loadDoc() {
            // creating instance of XMLHttpRequest()
            var xhttp = new XMLHttpRequest();
            xhttp.onreadystatechange = function () {
                if (this.readyState == 4 && this.status == 200) {
                    document.getElementById('loadAjax').innerHTML = this.responseText;
                }
            };
            xhttp.open('GET', 'ajax_demo.txt', true);
            xhttp.send();
        }
    </script>
    <script src='https://cdn.jsdelivr.net/npm/bootstrap@5.0.2/dist/js/bootstrap.bundle.min.js' integrity='sha384-MrcW6ZMFYlzcLA8Nl+NtUVF0sA7MsXsP1UyJoMp4YLEuNSfAP+JcXn/tWtIaxVXM' crossorigin='anonymous'></script>
</body>
</html>

Output

Before calling ajax

How to create the XMLHttpRequest object and what are the uses of XMLHttpRequest object in AJAX?

After calling ajax

How to create the XMLHttpRequest object and what are the uses of XMLHttpRequest object in AJAX?