jQuery Basics: A Guide for Beginners

What is jQuery?

jQuery is a fast, small, and feature-rich JavaScript library designed to simplify the client-side scripting of HTML. jQuery’s motto is “Write less, do more” because it allows developers to create animations, handle events, create AJAX applications, and much more, all with a simple and intuitive API that works across a multitude of browsers.

Why Use jQuery

While jQuery has both advantages and disadvantages, the choice between jQuery and native JavaScript (or another library or framework) will depend on the specific needs and constraints of the project.

Advantages of jQuery

1. Simplicity: jQuery simplifies tasks like DOM manipulation, event handling, AJAX calls, and animations, allowing developers to accomplish more with less code.
2. Cross-Browser Compatibility: jQuery automatically handles many of the inconsistencies between different browsers and browser versions, providing a consistent, cross-browser API.
3. Strong Community and Rich Ecosystem: jQuery has a vast community of developers, which means a lot of resources, such as tutorials, forums, and third-party plugins, are available. This support can make problem-solving much easier.
4. AJAX Support: jQuery provides a simple API for AJAX that is more intuitive and easy to use compared to the native JavaScript API.
5. Efficient for Large Projects: With larger projects that use a wide variety of jQuery features, jQuery can often be more efficient than native JavaScript due to its optimized methods and functions.
6. Chainability: jQuery allows developers to chain together actions and events, which can lead to cleaner and more concise code.

Disadvantages of jQuery

1. Loading Time: jQuery code has to wait for the jQuery library to load to run. Depending on the network speed and the server where jQuery is hosted, this could delay the execution of jQuery code.
2. File Size: The file size of jQuery, even when minified and gzipped, is around 90 KB. This might increase the load time, particularly on slower networks or mobile devices.
3. Unnecessary Features for Small Projects: For smaller projects that do not use all the features of jQuery, loading the entire library can be unnecessary and inefficient. Native JavaScript might be a more efficient solution in these cases.
4. Learning Curve: While jQuery does simplify many aspects of JavaScript, there is still a learning curve involved, especially for developers who are new to JavaScript.
5. Depreciation: With the evolution of modern JavaScript and the emergence of new libraries and frameworks like React, Vue, and Angular, some argue that jQuery is becoming outdated. Modern browsers and JavaScript itself have integrated many of the conveniences that jQuery offered.
6. Lack of Two-Way Data Binding: Unlike modern JavaScript frameworks like Angular or Vue.js, jQuery does not support two-way data binding, requiring developers to write additional code to update the UI whenever the data model changes and vice versa.

Installation

There are several ways to install jQuery, including using package managers like Composer, direct download and FTP upload to your server, or using a Content Delivery Network (CDN).

1. Installation Using Composer

Composer is a tool for dependency management in PHP. It allows you to declare the libraries your project depends on, and it will manage (install/update) them for you. Although jQuery is a JavaScript library, you can install it using Composer as well. Here’s how:

First, you need to have Composer installed. If it’s not installed yet, you can download it from getcomposer.org.

Once Composer is installed, you can require jQuery in your project by running the following command in your terminal:

composer require components/jquery

This command tells Composer to download the jQuery library and place it in your project’s “vendor” directory.

2. Installation via Direct Download and FTP

You can directly download jQuery from the official website (jquery.com). Once downloaded, you can upload the jQuery file to your server using File Transfer Protocol (FTP).

Here is a basic step-by-step guide:

1. Visit jquery.com and download the latest version of jQuery.
2. Unzip the downloaded file. You will get jquery.js and jquery.min.js files. The min.js file is a minified version of jQuery, which means it’s been compressed for a smaller file size. It’s exactly the same as the regular jquery.js file in terms of functionality.
3. Using your preferred FTP client (like FileZilla, WinSCP, etc.), upload the jquery.min.js file to your website’s directory.
4. In your HTML file, reference the uploaded jQuery file using a <script> tag. Here’s an example, if you uploaded the jQuery file to a directory named “js”:

<script src="/js/jquery.min.js"></script>

3. Installation Using a CDN

A CDN (Content Delivery Network) is a group of servers distributed globally, which delivers the content more efficiently to users. The user’s proximity to the server affects the site’s loading speed, so a CDN helps provide a fast site loading speed to users, regardless of their geographical location.

Warning: Using CDN’s requires your users to download files from other websites. This can have privacy concerns and may need to be addressed in a privacy statement.

Popular CDNs like Google and Microsoft host jQuery. To use jQuery from a CDN, include the following code in your HTML:

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>

Or

<script src="https://ajax.aspnetcdn.com/ajax/jQuery/jquery-3.5.1.min.js"></script>

Basics of Using jQuery

Once you have installed jQuery, you can start using it to add dynamic behavior to your website.

Document Ready Event

This is one of the most commonly used jQuery methods. It ensures that your code only runs once the DOM (Document Object Model) is ready for JavaScript code to execute:

$(document).ready(function(){
   // Your code here
});

Or you can use the shorthand:

$(function(){
   // Your code here
});

Selecting Elements

jQuery uses the $ function as a factory to create instances of jQuery objects.

CSS selector to this function to select HTML elements:

$('p') // Selects all <p> elements
$('.my-class') // Selects all elements with the class "my-class"
$('#my-id') // Selects the element with the id "my-id"“

Event Handling

You can handle events like clicks, mouse movements, form submissions, and more (Learn more About Events in Javascript, or Event Delegation in jQuery):

$('button').click(function() {
  alert("The button was clicked.");
});“

Animations and Effects

jQuery comes with several built-in methods for adding animations and effects:

$('p').hide(); // Hides all <p> elements
$('p').show(); // Shows all <p> elements
$('p').fadeOut(); // Fade out all <p> elements

Conclusion

jQuery simplifies the process of creating complex JavaScript applications, by providing easy-to-use, concise syntax and useful methods. It’s a powerful tool to have in your web development toolkit.