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Converting jQuery code to vanilla JavaScript

Posted on by Zubair Shaik

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Converting jQuery code to vanilla JavaScript can seem like a daunting task for developers who are accustomed to using jQuery for DOM manipulation, event handling, and AJAX requests. However, as modern browsers have improved their support for JavaScript, many of the features jQuery provided are now natively available in vanilla JavaScript, making it possible to build lightweight, efficient applications without relying on external libraries like jQuery.

This guide will explain in detail how to convert jQuery code to vanilla JavaScript. We will cover each method in jQuery and provide their equivalent solutions in vanilla JavaScript, ensuring you have a comprehensive understanding of how to transition your code. By the end of this guide, you will be able to easily convert your jQuery code into efficient vanilla JavaScript.

Table of Contents

  1. Introduction to jQuery and Vanilla JavaScript
    • What is jQuery?
    • Why Convert jQuery to Vanilla JavaScript?
    • Benefits of Using Vanilla JavaScript
  2. Getting Started with Vanilla JavaScript
    • Understanding Modern JavaScript Features
    • Differences Between jQuery and Vanilla JavaScript
  3. Converting Common jQuery Methods to Vanilla JavaScript
    • DOM Selection and Manipulation
    • Event Handling
    • AJAX Requests
    • Animations
  4. Converting jQuery Syntax to Vanilla JavaScript
    • $(document).ready() → DOMContentLoaded
    • $(‘#id’) → document.getElementById() and querySelector
    • $(‘.class’) → document.getElementsByClassName() and querySelectorAll
    • $(this) → this keyword in vanilla JS
  5. Working with Events
    • Binding Events in jQuery vs Vanilla JavaScript
    • Event Delegation
    • Event Handling with addEventListener
  6. Handling AJAX Requests
    • jQuery AJAX vs Fetch API
    • Error Handling in AJAX
    • Handling JSON Responses
  7. Animations and Effects
    • Animating Elements in jQuery vs CSS Transitions
    • jQuery Effects: fadeIn, fadeOut, slideDown, slideUp
    • CSS Animations vs jQuery Animations
  8. Advanced jQuery Features and Their Vanilla JavaScript Alternatives
    • jQuery Deferred Objects vs Promises
    • jQuery Ajax JSONP vs Fetch JSONP
  9. Benefits and Challenges of Using Vanilla JavaScript
    • Performance Benefits
    • Code Size Reduction
    • Compatibility Considerations
    • Learning Curve for Beginners
  10. Best Practices for Transitioning to Vanilla JavaScript
    • Progressive Enhancement
    • Testing and Debugging After Conversion
    • Refactoring Strategies for Complex jQuery Code
  11. Conclusion

1. Introduction to jQuery and Vanilla JavaScript

What is jQuery?

jQuery is a popular JavaScript library that simplifies HTML document traversal, event handling, animations, and AJAX requests. It was originally created to address the complexities of cross-browser compatibility, especially in earlier versions of Internet Explorer, where JavaScript implementations were inconsistent.

jQuery allows developers to write less code to achieve the same functionality. This is why it gained popularity quickly and became the go-to solution for JavaScript development in the past.

Why Convert jQuery to Vanilla JavaScript?

There are several reasons why developers are moving away from jQuery in favor of vanilla JavaScript:

  1. Browser Compatibility: Modern browsers now support most of the features that jQuery provides, making jQuery less necessary.
  2. Performance: Vanilla JavaScript is generally faster and more lightweight than using a library like jQuery, especially on mobile devices.
  3. Code Size: jQuery is a large library (around 90 KB minified), which can add unnecessary overhead to a web page. By switching to vanilla JavaScript, you reduce the size of your code.
  4. Learning and Control: Working directly with vanilla JavaScript allows developers to have a deeper understanding of how the language works, giving them more control over their code.

Benefits of Using Vanilla JavaScript

  1. Smaller File Size: Vanilla JavaScript does not require the inclusion of an external library, which reduces the overall size of the page.
  2. Faster Performance: JavaScript engines in modern browsers are optimized for vanilla JavaScript, making it faster and more efficient than using a library.
  3. Better Browser Support: Since modern browsers support most of the features that jQuery provides, you can rely on the native APIs for cross-browser compatibility.
  4. Future-Proof: As browser support continues to improve, using vanilla JavaScript is more future-proof than relying on an external library.

2. Getting Started with Vanilla JavaScript

Before converting jQuery code, it’s important to understand modern JavaScript features that make the conversion process easier.

Understanding Modern JavaScript Features

  • ES6+ Syntax: Features like let, const, arrow functions, template literals, and destructuring make JavaScript more concise and readable.
  • Query Selectors: document.querySelector and document.querySelectorAll allow for more powerful and flexible DOM selection.
  • Promises: For handling asynchronous operations, Promises provide a cleaner syntax compared to callbacks.

Differences Between jQuery and Vanilla JavaScript

  • jQuery provides shorthand methods for DOM manipulation, event handling, and AJAX, whereas vanilla JavaScript uses standard DOM and JavaScript methods.
  • Vanilla JavaScript requires more code to perform tasks like event delegation or DOM manipulation, but it offers better performance and fewer dependencies.

3. Converting Common jQuery Methods to Vanilla JavaScript

DOM Selection and Manipulation

In jQuery:

$('#element').addClass('active');
$('.button').css('color', 'red');

In Vanilla JavaScript:

document.getElementById('element').classList.add('active');
document.querySelectorAll('.button').forEach(function(button) {
  button.style.color = 'red';
});
  • getElementById(): Selects an element by its ID.
  • querySelector(): Selects the first element that matches a CSS selector.
  • querySelectorAll(): Selects all elements that match a CSS selector.

Event Handling

In jQuery:

$('#button').click(function() {
  alert('Button clicked!');
});

In Vanilla JavaScript:

document.getElementById('button').addEventListener('click', function() {
  alert('Button clicked!');
});
  • addEventListener(): Adds an event listener to an element in vanilla JavaScript.
  • Unlike jQuery, addEventListener() doesn’t automatically handle event delegation. You need to manually handle bubbling and delegation in vanilla JS.

AJAX Requests

In jQuery:

$.ajax({
  url: 'data.json',
  method: 'GET',
  success: function(data) {
    console.log(data);
  }
});

In Vanilla JavaScript:

fetch('data.json')
  .then(response => response.json())
  .then(data => console.log(data))
  .catch(error => console.error('Error:', error));
  • fetch(): A modern JavaScript API for making network requests. It returns a Promise, which can be handled using .then() and .catch().

Animations

In jQuery:

$('#element').fadeIn();
$('#element').slideUp();

In Vanilla JavaScript:

document.getElementById('element').style.display = 'block';
document.getElementById('element').style.transition = 'height 0.5s';
document.getElementById('element').style.height = '0px'; // Example of slide up
  • CSS Transitions and Animations: Instead of relying on jQuery’s animation methods, you can use CSS transitions or animations for smoother, more performant animations.

4. Converting jQuery Syntax to Vanilla JavaScript

$(document).ready() → DOMContentLoaded

In jQuery:

$(document).ready(function() {
  console.log('Document is ready');
});

In Vanilla JavaScript:

document.addEventListener('DOMContentLoaded', function() {
  console.log('Document is ready');
});

The DOMContentLoaded event fires when the HTML document has been completely loaded, but before stylesheets, images, and subframes are finished loading.

$(‘#id’) → document.getElementById() and querySelector

In jQuery:

$('#element');

In Vanilla JavaScript:

document.getElementById('element');

Or, using querySelector:

document.querySelector('#element');

$(‘.class’) → document.getElementsByClassName() and querySelectorAll

In jQuery:

$('.button');

In Vanilla JavaScript:

document.getElementsByClassName('button');

Or, using querySelectorAll:

document.querySelectorAll('.button');

$(this) → this keyword in vanilla JS

In jQuery:

$('.button').click(function() {
  console.log($(this).text());
});

In Vanilla JavaScript:

document.querySelectorAll('.button').forEach(function(button) {
  button.addEventListener('click', function() {
    console.log(this.textContent);
  });
});

The this keyword in vanilla JavaScript works similarly to jQuery’s $(this).

5. Working with Events

Binding Events in jQuery vs Vanilla JavaScript

In jQuery:

$('#button').on('click', function() {
  alert('Button clicked!');
});

In Vanilla JavaScript:

document.getElementById('button').addEventListener('click', function() {
  alert('Button clicked!');
});

Both methods are used to bind events, but in vanilla JavaScript, you must specify the event type (e.g., click, mouseover) explicitly.

Event Delegation

In jQuery:

$('#parent').on('click', '.child', function() {
  alert('Child clicked!');
});

In Vanilla JavaScript:

document.getElementById('parent').addEventListener('click', function(event) {
  if (event.target.matches('.child')) {
    alert('Child clicked!');
  }
});

Event delegation in vanilla JavaScript is done by checking if the clicked element matches a selector using matches().

6. Handling AJAX Requests

Converting AJAX requests to vanilla JavaScript can be done using the Fetch API. This modern API is more flexible and easier to work with than jQuery’s AJAX methods. It supports promises, making it a cleaner choice for handling asynchronous operations.

Example: Fetching JSON Data

fetch('data.json')
  .then(response => response.json())
  .then(data => console.log(data))
  .catch(error => console.log('Error fetching data:', error));

7. Animations and Effects

In jQuery:

$('#element').fadeIn();
$('#element').slideUp();

In Vanilla JavaScript: You can replicate these animations using CSS transitions or JavaScript animations:

document.getElementById('element').style.transition = 'opacity 0.5s';
document.getElementById('element').style.opacity = '1';

CSS Transitions vs jQuery Animations

CSS transitions are more performant and allow you to control animations with less JavaScript.

8. Advanced jQuery Features and Their Vanilla JavaScript Alternatives

jQuery Deferred Objects vs Promises

In jQuery:

$.Deferred(function() {
  this.resolve();
}).then(function() {
  console.log('Resolved!');
});

In Vanilla JavaScript:

new Promise(function(resolve, reject) {
  resolve();
}).then(function() {
  console.log('Resolved!');
});

9. Benefits and Challenges of Using Vanilla JavaScript

Performance Benefits

  • Vanilla JavaScript is faster because it has no dependency overhead.
  • Less code execution time, leading to faster page loads.

Code Size Reduction

  • Removing jQuery reduces the amount of JavaScript being loaded on the page.

Learning Curve

  • Converting from jQuery to vanilla JavaScript may be challenging initially, especially if you’re used to jQuery’s syntax.

10. Best Practices for Transitioning to Vanilla JavaScript

  • Progressive Enhancement: Gradually convert jQuery code to vanilla JavaScript, testing functionality at each step.
  • Testing: After converting, thoroughly test the functionality of the page to ensure everything works as expected.
  • Refactoring: For complex jQuery code, break down tasks into smaller functions that can be converted to vanilla JavaScript incrementally.

Converting jQuery code to vanilla JavaScript offers many benefits, including improved performance, reduced code size, and better compatibility with modern web standards. By understanding the differences between jQuery and vanilla JavaScript, and following the step-by-step conversion process outlined above, developers can build more efficient, lightweight web applications without relying on external libraries.

With this guide, you are now equipped to confidently convert jQuery code to vanilla JavaScript for better performance, maintainability, and scalability.

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