What are the best ways to use multiple JavaScript libraries in your web application?

1 Load libraries asynchronously

One of the first things you should do when using multiple JavaScript libraries in your web application is to load them asynchronously. This means that the browser does not wait for the library to load before executing the rest of the code, but instead loads it in the background while the web page is rendering. This can improve your web application's speed, responsiveness, and user experience, as well as avoid blocking the main thread. To load libraries asynchronously, you can use the async or defer attributes in your script tags, or use a module loader like RequireJS or Webpack.

2 Use namespaces and closures

Another way to use multiple JavaScript libraries in your web application is to use namespaces and closures. Namespaces are a way of organizing your code into logical groups or modules, and avoiding global variables that can clash with other libraries or scripts. For example, you can use the var keyword to create a namespace object, and then attach your library's functions and variables to it. Closures are a way of creating private variables and functions that are only accessible within a certain scope, and preventing them from polluting the global scope. For example, you can use an immediately invoked function expression (IIFE) to create a closure that wraps your library's code and exposes only what you need.

3 Use noConflict mode

Some JavaScript libraries, such as jQuery, offer a noConflict mode that allows you to use them without interfering with other libraries that may use the same variable names or symbols. For example, jQuery uses the $ symbol as a shorthand for its main function, but other libraries may also use it for different purposes. To avoid conflicts, you can use the noConflict method to release the $ symbol and assign it to another variable of your choice. Then, you can use that variable instead of $ to access jQuery's functionality.

4 Use compatibility libraries

Another option to use multiple JavaScript libraries in your web application is to use compatibility libraries that provide a common interface or syntax for different libraries. For example, you can use React Hooks for jQuery, which is a library that allows you to use React hooks with jQuery elements and methods. This can make your code more consistent, readable, and maintainable, as well as reduce the learning curve for using different libraries.

5 Choose libraries wisely

Finally, one of the most important ways to use multiple JavaScript libraries in your web application is to choose them wisely. Before adding a new library to your web application, you should consider its purpose, size, performance, compatibility, documentation, and popularity. You should also evaluate if you really need the library, or if you can achieve the same functionality with native JavaScript or a smaller and simpler library. You should avoid using too many libraries, as they can increase your web application's loading time, complexity, and potential for errors. You should also update your libraries regularly, and remove any unused or outdated ones.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?