Tips and tricks for optimizing JavaScript performance

In the previous five years, JavaScript has emerged as the leading scripting language among the modern developers. JavaScript is everywhere, from servers, games, websites, operating systems, and even robots also. Not just that, JavaScript is also one of the most well known languages used on GitHub.

Considering the consistently developing popularity of JavaScript in the domains of web and mobile application development, it gets essential for JavaScript developers to be updated with the best performance practices. Hence let us discuss some tips for improving Javascript performance.

Also know- Top 6 JavaScript Date Libraries.

Tips for improving Javascript performance- 

Tips and tricks for optimizing Javascript performance

1. Learn asynchronous programming-

To fetch the data, your application would require a few internal calls to various APIs. One way to solve this issue is by getting different middleware for each function. JavaScript has a great deal of synchronous components since it’s single-threaded. These components have the capability to lock the complete application.

However, JavaScript’s async.js feature helps in efficient management of asynchronous codes. This causes async code to get pushed to an event queue where it fires after the execution of all other code. However, even with JavaScript’s async feature, there’s a possibility of using an external library that could return to the synchronous blocking call. And, this could affect the general performance. 

The most ideal approach to handle this is to consistently use asynchronous APIs in your code. In any case, you should always remember that understanding the complexities of async programming is often challenging for the novices.

2. Avoid using global variables-

Since the scripting engine needs to look through the scope while referencing global variables from within function or another scope, the variable will be destroyed when the local scope is lost. If variables in the global scope can not continue through the lifetime of the script, the performance will be improved.

3. Keep codes light and small-

To maintain the high performance of mobile applications, it’s better to keep the code light and also reduced. Keeping codes light and small would decrease the latency and boost up the speed. While you’re in a development stage, you should ask yourself these questions below.

  • Do I really need this module?
  • Can I do this in a simpler manner?
  • Why am I using this framework?
  • Is this worth the overhead?

Another method to optimize the application’s performance is by shrinking and diminishing various JS files into one. For instance, if your application has seven JavaScript files, then the browser will need to make seven different HTTP requests with the goal that it can fetch them all. To avoid this, you can just convert the seven files into one streamlined one.

4. Cache in the browser-

There are two choices for doing this. The first is to use the JavaScript Cache API, which we can use by installing a service worker. The second is to use the HTTP protocol cache. Scripts are frequently used to access a specific object. By storing a repeated access object inside a user-defined variable, as well as using a variable in subsequent references to that object, performance improvement can be achieved immediately.

5. Avoid using too much memory-

You should consistently try to limit memory use to what is necessary, because it is possible to know how much memory is required by the device being used to run your application. Whenever your code requests that the browser rserve new memory, the browser’s garbage collector is executed, and JavaScript is stopped. If this happens frequently, the page will work very slowly.

6. Minimize DOM access-

Interaction of host browser with objects (DOM) that takes place outside the JavaScript native environment results in a lot of performance slack and unpredictability. This happens since the browser has to refresh every time. To avoid this, you can just minimize the access of DOM. There are some ways by which you achieve this. For instance, you can store references to the browser objects or you can decrease the general DOM traversal trips.

7. Remove unused JavaScript-

This step won’t just reduce transmission time, yet additionally the time it takes for the browser to analyze and compile the code. To do this, you should consider the following points: If you detect a functionality that isn’t being used by users, it’s a better practice to remove it with all its associated JavaScript code, so the website will load faster and users will have a superior experience. -It is also possible that a library was included by mistake and is not vital, or that you have dependencies that offer some functionality that is natively available in all browsers, without the need to use extra code.

8. Use web workers when you need to execute code that needs a lot of execution time-

According to the Mozilla Developers Network (MDN) documentation: “Web Workers makes it possible to run a script operation in a background thread separate from the main execution thread of a web application. The benefit of this is that laborious processing can be performed in a different thread, allowing the main (usually the UI) thread to run without being blocked/slowed down.”

Web workers allow your code to perform processor-intensive calculations without blocking the UI thread. Web Workers allow you to bring forth new threads and delegate work to these threads for efficient performance. This way, long running tasks which would typically block other tasks are passed off to a worker and the main thread can run without being blocked.

9. Eliminate memory leaks-

In case of a memory leak, the loaded page will use more memory and eventually occupy all the available memory in the device. This would impact the general performance adversely. You might be familiar with this type of failure that occurs on a page with an image slide.

There are tools that analyse whether your website is leaking memory or not. Chrome Dev Tools is one of such tools which records the timeline in the performance tab. Normally, the pieces of the removed DOM from the page are liable for memory leaks because they have some variable which is responsible for reference which prevents the garbage collector from eliminating them.

10. Event Delegation implementation-

Event Delegation makes it simpler to use a single event handler which eventually helps in proficient management of a type of event for the whole page. Without Event Delegation, large web applications can stop because of the presence of some event handlers. Event Delegation accompanies numerous advantages, for example, less functionality to manage, less memory required to process, and less ties among DOM and code.


These are the top 10 tips to improve Javascript performance and help you to provide superior JavaScript development services. There can be few others too. If they all are implemented together, at that point you’ll observe a tremendous improvement in the speed of your JavaScript web development and applications.

If you’re looking for any further assistance then you can contact us. We have dedicated javascript expert developers to provide you the optimized web solution. Connect with Solace for an effective and efficient solution. We will be happy to help you.

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