Define AJAX. How do you consume web services using AJAX?

Puran Katuwal . 3 days ago

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AJAX stands for Asynchronous JavaScript and XML. AJAX is not a new programming language, but a new way to use existing standards. AJAX is not a single technology but group of technologies such as: HTML/XHTML, CSS, JavaScript/ DOM. AJAX is a technique for creating fast and dynamic web pages. AJAX allows web pages to be updated asynchronously by exchanging small amounts of data with the server behind the scenes. This means that it is possible to update parts of a web page, without reloading the whole page. Classic web pages, (which do not use AJAX) must reload the entire page if the content should change.

To consume web services using AJAX (Asynchronous JavaScript and XML), you can follow these steps: Create an XMLHttpRequest object: Use the XMLHttpRequest object (or the newer fetch API) to make HTTP requests to the server. This object provides methods and properties to send and receive data asynchronously. Set the request parameters: Open the connection to the server and specify the HTTP method (GET, POST, etc.), the URL of the web service, and any optional parameters or headers required by the service. Define a callback function: Set up a callback function that will handle the response from the server. This function will execute when the server's response is received. Send the request: Send the request to the server using the send() method of the XMLHttpRequest object. If you're using the fetch API, you can use the fetch() function.Process the response: In the callback function, process the response received from the server. This may involve parsing the response data (XML, JSON, etc.) and updating the web page dynamically. Here's an example of consuming a web service using AJAX in JavaScript:

 var xhr = new XMLHttpRequest();
var url = "https://api.example.com/data"; // URL of the web service
xhr.open("GET", url, true); // Open the connection
xhr.onreadystatechange = function() {
if (xhr.readyState === XMLHttpRequest.DONE) {
if (xhr.status === 200) {
var response = JSON.parse(xhr.responseText);
// Process the response data and update the web page
console.log(response);
} else {
console.log("Error: " + xhr.status);
}
}
};
xhr.send(); // Send the request

In this example, we create an XMLHttpRequest object, specify the URL of the web service, define a callback function to handle the response, and send the request using the send() method. Once the response is accordingly. received, we parse the JSON data and update the e the web page.