Delve into the intriguing world of Computer Science with a clear, in-depth examination of AJAX - a core set of technologies pivotal in web development. This comprehensive guide illuminates the question, 'What is Ajax?' and offers an unrivalled exploration into its definition, history, principles, and key characteristics. By understanding its role in real-world scenarios and how it compares to other technologies such as JQuery, you'll gain a well-rounded perspective on Ajax's impact on the digital landscape. Lastly, explore practical examples and applications to see Ajax technique in action, bridging the gap between theory and practice. Get ready to uncover the enigmatic 'John Doe' of Computer Programming in a way that is both enlightening and engaging.
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Jetzt kostenlos anmeldenDelve into the intriguing world of Computer Science with a clear, in-depth examination of AJAX - a core set of technologies pivotal in web development. This comprehensive guide illuminates the question, 'What is Ajax?' and offers an unrivalled exploration into its definition, history, principles, and key characteristics. By understanding its role in real-world scenarios and how it compares to other technologies such as JQuery, you'll gain a well-rounded perspective on Ajax's impact on the digital landscape. Lastly, explore practical examples and applications to see Ajax technique in action, bridging the gap between theory and practice. Get ready to uncover the enigmatic 'John Doe' of Computer Programming in a way that is both enlightening and engaging.
Ajax, an acronym for Asynchronous JavaScript and XML, is not a programming language but is a set of web development techniques utilising manifold technologies.
let xhr = new XMLHttpRequest(); xhr.open('GET', 'ajax_info.txt', true); xhr.send();Fascinating, isn't it? Let's dive into Ajax history now.
Fun fact: Ajax was officially termed and popularised by Jesse James Garrett in an article in February 2005, six years after its introduction!
1999 | Microsoft introduced 'Ajax' with Internet Explorer 5. |
2002 | Mozilla followed with their implementation on the new XMLHttpRequest object. |
2005 | Ajax received its official name and fame after an article by Jesse James Garrett. |
Today | Well-utilised and integral in many JavaScript frameworks and in web development. |
A familiar example of Ajax in daily use is when you're typing in a Google search. The suggested search terms that start appearing as you type are fetched using Ajax.
The first principle of Ajax hinges on the utilisation of the XMLHttpRequest object. This JavaScript object allows you to send HTTP or HTTPS requests to a web server and load the server response data back into the script.
let xhr = new XMLHttpRequest(); xhr.open('GET', 'ajax_info.txt', true); xhr.onreadystatechange = function() { if (xhr.readyState == 4 && xhr.status == 200) { console.log(xhr.responseText); } }; xhr.send();Next comes the asynchronous nature of Ajax. The 'true' in xhr.open('GET', 'ajax_info.txt', true); means the request is asynchronous. Here, the JavaScript does not have to wait for the server response and can proceed to execute other scripts. Meanwhile, HTML and CSS handle presentation, while the Document Object Model (DOM) is crucial for dynamic interactions. Ajax manipulates the DOM to refresh a portion of a page rather than reloading the whole page. Lastly, data interchange was initially facilitated with XML. Today, however, JSON is more commonly used due to its efficiency and lightness.
GitHub is a prime example of Ajax's power. When you star a repository, the website doesn't reload. Instead, the star count updates instantly—an Ajax request runs behind the scenes.
function starRepo() { let xhr = new XMLHttpRequest(); xhr.open('POST', 'starRepo.php', true); xhr.onreadystatechange = function() { if (xhr.readyState == 4 && xhr.status == 200) { //Update the star count on the page } }; xhr.send(); }Another practical usage is the "load more" functionality seen on many websites.
For instance, when you're scrolling through your Facebook news feed, more posts load as you reach the bottom. Here's what's actually happening: an Ajax request fetches and loads the additional posts without reloading the entire page!
The initial and most important characteristic is Ajax’s asynchronous nature. This essentially means that the web application continues to work and remain responsive even when Ajax is communicating in the background with the server.
A widespread use of Ajax is in Autocomplete suggestions as seen in Google Search. When you start typing into the search bar, Google quickly provides relevant suggestions despite having billions of indexed web pages. This happens in real-time, without refreshing the page. This mechanism combines Ajax's asynchronous operations, use of JavaScript and DOM, XHR requests, and data sortation in JSON or XML.
//JavaScript pseudo-code let search = function(input) { let xhr = new XMLHttpRequest(); xhr.open('GET', 'google.com/complete/search?q=' + input, true); xhr.onreadystatechange = function() { if (xhr.readyState == 4 && xhr.status == 200) { let suggestions = JSON.parse(xhr.responseText); //Code to update the DOM with these suggestions } }; xhr.send(); };Another application of Ajax shines in user registration forms where the availability of a username needs to be checked without reloading the page.
Websites like Twitter and Instagram instantly inform you about the availability of usernames. They do so by sending an Ajax request to the server with the entered username and updating the DOM based on the server's response—demonstrating the asynchronous operation, JavaScript and DOM usage, XHR requests, and JSON data formats.
let usernameCheck = function(input) { let xhr = new XMLHttpRequest(); xhr.open('POST', 'checkUsername.php', true); xhr.onreadystatechange = function() { if (xhr.readyState == 4 && xhr.status == 200) { if(xhr.responseText === "taken") { //Code to update the DOM indicating username is taken } } }; xhr.send('username=' + input); };These examples showcase Ajax characteristics in play, revealing their combined power in enhancing user experience and application efficiency. It's not just about the background theory—it’s about how the theory applies practically to the realm of web technologies in daily life.
Ajax, as you may recall, stands for Asynchronous JavaScript and XML. It is a set of web development techniques for creating interactive applications. On the other hand, JQuery is a fast, small, and feature-rich JavaScript library that simplifies HTML document traversal, event handling, and Ajax interactions.
let xhr = new XMLHttpRequest(); xhr.open('GET', 'ajax_info.txt', true); xhr.onreadystatechange = function() { if (xhr.readyState == 4 && xhr.status == 200) { let data = JSON.parse(xhr.responseText); // Manipulate the DOM with data } }; xhr.send();On the flip side, JQuery simplifies this process by abstracting a lot of the details behind methods. The same Ajax interaction can be achieved with fewer lines of code using JQuery:
$.ajax({ url: 'ajax_info.txt', type: 'GET', dataType: 'json', success: function(data) { // Manipulate the DOM with data } });Both Ajax and JQuery contribute towards enhancing web development and user experience but from different angles. Where Ajax acts as a method of implementing asynchronous operations, JQuery simplifies and boosts this process with its user-friendly syntax and in-built functions. In their usage, they often overlap, with JQuery incorporating Ajax methods to facilitate simpler functional implementation. Ajax and JQuery are not synonymous but complementary, each making its own unique contribution to the broader territory of web development. The understanding of both aids in developing more interactive and efficient websites, enhancing overall user experience. Get ready to play with these fantastic tools and harness their power in your web development journey!
Therefore, the principal use cases of Ajax are:
let fetchGitHubRepos = function(username) { let xhr = new XMLHttpRequest(); xhr.open('GET', 'https://api.github.com/users/'+username+'/repos', true); xhr.onreadystatechange = function() { if (xhr.readyState == 4 && xhr.status == 200) { let repos = JSON.parse(xhr.responseText); //Function to display these repositories on the page } }; xhr.send(); };Another example of Ajax in action lies in the realm of e-commerce websites. When you filter products on e-commerce websites like Amazon or eBay, Ajax is at play. Instead of refreshing the entire page for each filtering criterion (like price, brand, or rating), Ajax fetches the filtered product data from the server and reloads only the relevant section of the page. While you explore computer science and harness these Ajax techniques, you’ll see it go beyond improving website efficiency and user experience—it’s truly about empowering websites with seamless interactive capabilities! These solid examples reinforce the strength of Ajax, making its principles highly relevant and essential to modern web development.
What does AJAX stand for in web development and what is its main functionality?
AJAX stands for Asynchronous JavaScript and XML. It's a set of web development techniques that allow for the creation of asynchronous web applications, meaning that data can be sent and received from a server without interfering with the display and behaviour of the existing page.
What are the main components of an AJAX application?
The main components of an AJAX application are HTML (or XHTML) and CSS for presentation, The Document Object Model (DOM) for dynamic display and interaction, XML for the interchange of data and XSLT for its manipulation, the XMLHttpRequest object for asynchronous communication, and JavaScript to bring these components together.
Who introduced AJAX and when was it popularised?
AJAX was introduced in 1999 by Microsoft with their Internet Explorer 5. It was named and popularised by Jesse James Garrett in an article in February 2005.
What is the first principle of Ajax programming?
The first principle of Ajax programming hinges on the utilisation of the XMLHttpRequest object. This JavaScript object allows you to send HTTP or HTTPS requests to a web server and load the server response data back into the script.
What does the 'true' indicate in the xhr.open('GET', 'ajax_info.txt', true); function in Ajax?
The 'true' in xhr.open('GET', 'ajax_info.txt', true); means the request is asynchronous. The JavaScript does not have to wait for the server response and can proceed to execute other scripts.
How has data interchange in Ajax evolved over time?
Data interchange in Ajax was initially facilitated with XML. Today, however, JSON is more commonly used due to its efficiency and lightness.
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