How To Replace All Javascript

JavaScript is an indispensable part of modern web development, but there are times when you might want to replace a JavaScript library or even the entire JavaScript codebase of a project. In this post, we’ll guide you through the process of replacing all JavaScript in a web application, whether you’re refactoring, upgrading, or just starting from scratch.

Step 1: Identify the JavaScript dependencies

Before you can replace all JavaScript in your project, you need to know what you’re working with. Start by identifying the various JavaScript libraries and plugins used in your project. These may include:

  • jQuery, Angular, React, or Vue.js for DOM manipulation and app structure
  • Bootstrap or Materialize for styling and UI components
  • Chart.js or D3.js for data visualization
  • Various utility libraries like Lodash, Moment.js, or Axios

Make a list of these libraries and their versions, as you’ll want to ensure compatibility if you’re upgrading or replacing them.

Step 2: Remove or replace the libraries

Once you have a clear understanding of your project’s dependencies, you can begin the process of removing or replacing them. This may involve:

  • Upgrading to a newer version of a library (e.g., upgrading from AngularJS to Angular)
  • Replacing a library with an alternative (e.g., replacing jQuery with Vanilla JavaScript or a smaller library like Zepto.js)
  • Removing a library entirely if it’s no longer needed

Be sure to update your project’s package.json file and run npm install or yarn install to ensure that your new dependencies are properly installed.

Step 3: Update your codebase

With your dependencies sorted, it’s time to update your codebase. This will likely involve a mix of refactoring existing code and rewriting sections that rely on removed or replaced libraries.

For example, if you’ve removed jQuery in favor of vanilla JavaScript, you’ll need to rewrite sections of your code that use jQuery’s $ function and other jQuery-specific methods. Similarly, if you’ve upgraded from AngularJS to Angular, you’ll need to refactor your code to use the new framework’s syntax and APIs.

Here’s an example of how you might convert a simple jQuery click handler to vanilla JavaScript:

// jQuery version
$('button').click(function() {
  console.log('Button clicked!');

// Vanilla JavaScript version
document.querySelector('button').addEventListener('click', function() {
  console.log('Button clicked!');

Step 4: Test your changes

Finally, it’s essential to thoroughly test your updated codebase to ensure that everything still works as expected. This should involve:

  • Manual testing in multiple browsers and browser versions
  • Running your existing test suite, if you have one
  • Writing new tests for any new or updated functionality

As you test, be prepared to encounter bugs and edge cases that require additional refactoring or rewriting. This is a normal part of the process and should be expected when making significant changes to your codebase.


Replacing all JavaScript in a web application can be a challenging and time-consuming process, but it’s often necessary to stay up to date with modern best practices and libraries. By following the steps outlined in this post, you’ll be well on your way to a more maintainable, efficient, and modern codebase.