Ajax in JQuery

Ajax (Asynchronous JavaScript and XML) is a powerful technique for making asynchronous requests to the server without reloading the entire webpage. In this chapter, we will explore how to work with Ajax in jQuery, from basic concepts to advanced techniques.

Introduction to Ajax

Ajax allows web pages to dynamically update content by making requests to the server in the background. This enables smoother and more interactive user experiences, as only specific parts of the page are updated without requiring a full page reload.

Basic Ajax Concepts

Making GET Requests

				
					$.ajax({
  url: 'https://api.example.com/data',
  method: 'GET',
  success: function(response) {
    console.log(response);
  },
  error: function(xhr, status, error) {
    console.error(status, error);
  }
});

Explanation:

  • This code snippet sends a GET request to the specified URL (https://api.example.com/data).
  • Upon success, the success callback function is executed, logging the response data to the console.
  • If an error occurs during the request, the error callback function is executed, logging the status and error message.

Making POST Requests

				
					$.ajax({
  url: 'https://api.example.com/save',
  method: 'POST',
  data: { name: 'John', age: 30 },
  success: function(response) {
    console.log('Data saved:', response);
  },
  error: function(xhr, status, error) {
    console.error('Error saving data:', status, error);
  }
});

Explanation:

  • This code snippet sends a POST request to the specified URL (https://api.example.com/save) with data { name: 'John', age: 30 }.
  • Upon success, the success callback function is executed, logging a success message along with the response data.
  • If an error occurs during the request, the error callback function is executed, logging an error message.

Advanced Ajax Techniques

Handling JSON Responses

				
					$.ajax({
  url: 'https://api.example.com/data',
  method: 'GET',
  dataType: 'json',
  success: function(response) {
    console.log('JSON Response:', response);
  },
  error: function(xhr, status, error) {
    console.error('Error fetching JSON data:', status, error);
  }
});

Explanation:

  • By specifying dataType: 'json', jQuery automatically parses the response as JSON.
  • This allows you to directly work with the JSON data within the success callback function.

Working with Headers

				
					$.ajax({
  url: 'https://api.example.com/data',
  method: 'GET',
  headers: { 'Authorization': 'Bearer <token>' },
  success: function(response) {
    console.log('Authenticated Request:', response);
  },
  error: function(xhr, status, error) {
    console.error('Error fetching data:', status, error);
  }
});

Explanation:

  • You can include custom headers in your Ajax requests using the headers option.
  • This is useful for sending authentication tokens, API keys, or any other custom headers required by the server.

Practical Examples of Working with Ajax in jQuery

Example 1: Fetching Data from a Remote Server

Suppose you have a web page that needs to fetch user data from a remote server and display it dynamically. Here’s how you can accomplish this using Ajax in jQuery:

				
					<!DOCTYPE html>
<html lang="en">
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    <meta charset="UTF-8">
    <title>User Data</title> <script type="litespeed/javascript" data-src="https://code.jquery.com/jquery-3.6.0.min.js"></script> </head>
<body>
    <div id="user-info"></div> <script type="litespeed/javascript">$(document).ready(function(){$.ajax({url:'https://api.example.com/users',method:'GET',success:function(response){response.forEach(function(user){$('#user-info').append('<p>Name: '+user.name+', Email: '+user.email+'</p>')})},error:function(xhr,status,error){console.error('Error fetching user data:',status,error)}})})</script> <script data-no-optimize="1">!function(t,e){"object"==typeof exports&&"undefined"!=typeof module?module.exports=e():"function"==typeof define&&define.amd?define(e):(t="undefined"!=typeof globalThis?globalThis:t||self).LazyLoad=e()}(this,function(){"use strict";function e(){return(e=Object.assign||function(t){for(var e=1;e<arguments.length;e++){var n,a=arguments[e];for(n in a)Object.prototype.hasOwnProperty.call(a,n)&&(t[n]=a[n])}return t}).apply(this,arguments)}function i(t){return e({},it,t)}function o(t,e){var n,a="LazyLoad::Initialized",i=new t(e);try{n=new CustomEvent(a,{detail:{instance:i}})}catch(t){(n=document.createEvent("CustomEvent")).initCustomEvent(a,!1,!1,{instance:i})}window.dispatchEvent(n)}function l(t,e){return t.getAttribute(gt+e)}function c(t){return l(t,bt)}function s(t,e){return function(t,e,n){e=gt+e;null!==n?t.setAttribute(e,n):t.removeAttribute(e)}(t,bt,e)}function r(t){return s(t,null),0}function u(t){return null===c(t)}function d(t){return c(t)===vt}function f(t,e,n,a){t&&(void 0===a?void 0===n?t(e):t(e,n):t(e,n,a))}function _(t,e){nt?t.classList.add(e):t.className+=(t.className?" 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</html>

Explanation:

  • This script sends a GET request to https://api.example.com/users to fetch user data.
  • Upon success, it iterates over the array of user objects in the response and appends each user’s name and email to the #user-info element in the HTML.

Suppose the server responds with the following JSON data:

				
					[
  { "name": "Alice", "email": "alice@example.com" },
  { "name": "Bob", "email": "bob@example.com" },
  { "name": "Charlie", "email": "charlie@example.com" }
]

The output in the browser will be:

				
					Name: Alice, Email: alice@example.com
Name: Bob, Email: bob@example.com
Name: Charlie, Email: charlie@example.com

Example 2: Submitting Form Data via Ajax

Suppose you have a form on your webpage and you want to submit the form data to a server endpoint without refreshing the page. Here’s how you can achieve this using Ajax in jQuery:

				
					<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Form Submission</title> <script type="litespeed/javascript" data-src="https://code.jquery.com/jquery-3.6.0.min.js"></script> </head>
<body>
    <form id="myForm">
        <label for="name">Name:</label>
        <input type="text" id="name" name="name"><br><br>
        <label for="email">Email:</label>
        <input type="email" id="email" name="email"><br><br>
        <input type="submit" value="Submit">
    </form> <script type="litespeed/javascript">$(document).ready(function(){$('#myForm').submit(function(event){event.preventDefault();var formData=$(this).serialize();$.ajax({url:'https://api.example.com/submit',method:'POST',data:formData,success:function(response){console.log('Form submitted successfully:',response)},error:function(xhr,status,error){console.error('Error submitting form:',status,error)}})})})</script> <script data-no-optimize="1">!function(t,e){"object"==typeof exports&&"undefined"!=typeof module?module.exports=e():"function"==typeof define&&define.amd?define(e):(t="undefined"!=typeof globalThis?globalThis:t||self).LazyLoad=e()}(this,function(){"use strict";function e(){return(e=Object.assign||function(t){for(var e=1;e<arguments.length;e++){var n,a=arguments[e];for(n in a)Object.prototype.hasOwnProperty.call(a,n)&&(t[n]=a[n])}return t}).apply(this,arguments)}function i(t){return e({},it,t)}function o(t,e){var n,a="LazyLoad::Initialized",i=new t(e);try{n=new CustomEvent(a,{detail:{instance:i}})}catch(t){(n=document.createEvent("CustomEvent")).initCustomEvent(a,!1,!1,{instance:i})}window.dispatchEvent(n)}function l(t,e){return t.getAttribute(gt+e)}function c(t){return l(t,bt)}function s(t,e){return function(t,e,n){e=gt+e;null!==n?t.setAttribute(e,n):t.removeAttribute(e)}(t,bt,e)}function r(t){return s(t,null),0}function u(t){return null===c(t)}function d(t){return c(t)===vt}function f(t,e,n,a){t&&(void 0===a?void 0===n?t(e):t(e,n):t(e,n,a))}function _(t,e){nt?t.classList.add(e):t.className+=(t.className?" 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</html>

Explanation:

  • This script intercepts the form submission event using $('#myForm').submit(function(event) {...}).
  • It prevents the default form submission behavior using event.preventDefault().
  • Form data is serialized using $(this).serialize() and sent as the data parameter in the Ajax request.
  • Upon success, a success message is logged to the console. If an error occurs, an error message is logged.

Suppose the server responds with a success message: Output

				
					Form submitted successfully: Data saved successfully

Example 3: Fetching JSON Data and Updating UI

Suppose you have a web page that displays weather information fetched from a JSON API. Here’s how you can implement this using Ajax in jQuery:

				
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<html lang="en">
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</html>

Explanation:

  • This script sends a GET request to https://api.example.com/weather to fetch weather data in JSON format.
  • Upon success, it updates the #weather-info div with temperature and condition information fetched from the JSON response.
  • If an error occurs, an error message is logged to the console

Suppose the server responds with the following JSON data:

				
					{
  "temperature": 25,
  "condition": "Sunny"
}

The output in the browser will be:

				
					Temperature: 25°C
Condition: Sunny

Ajax is a crucial tool in modern web development, enabling dynamic and interactive web applications. With jQuery, working with Ajax becomes simpler and more streamlined. By mastering basic Ajax concepts like making GET and POST requests, handling JSON responses, and utilizing advanced techniques such as custom headers, developers can create powerful and responsive web experiences. Happy coding !❤️

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