Top 11 Tips For Improving Javascript Performance

In the past few years, JavaScript has become a leading scripting language among the next generation developers. JavaScript is used everywhere, from servers, websites, operating systems, and even robots. JavaScript is one of the most popular languages that is used on GitHub.

Considering the ever-growing popularity of JavaScript in web and mobile app development, it becomes crucial for JavaScript developers to stay updated with the latest technology.

That’s why we are providing you the top 15 tips that will improve your JavaScript performance.


  1. Learn asynchronous programming

To retrieve the data, your app would need several calls to a number of APIs. One way to solve this problem is by getting different middleware for each function. JavaScript has a lot of synchronous components since it’s single-threaded. These components have the capability to secure the whole app.


However, JavaScript’s async.js feature helps in efficient management of codes. This causes async code to get pushed to an event where it fires after the execution of all other codes. However, even with JavaScript\’s async feature, there’s still a possibility of using a library that could revert to the synchronous blocking call. And this could have an adverse effect on the overall performance.


  1. Gzip compression

Gzip is a software application that is used by most clients and servers for compression and decompression. When a browser which is compatible with gzip requests a resource, the server compresses the response before it sends it to the browser. Gzip compresses the big JavaScript files and saves the bandwidth which eventually reduces the latency & time lag and enhances the application’s overall performance.



  1. Define variables locally

Whenever you call a certain function, the variables that are used to define that function are stored inside. Variables can be categorized into two types.


  1. Local variables that are defined only within themselves.
  2. Global variables that are used throughout the script.


At the time when you’re calling a function, the browser does an activity which is termed as scope lookup. With the increase in the number of scopes in the scope chain, there’s also an increase in the amount of time taken to access variables that are outside the current scope.


  1. Keep codes light and small

To maintain the high performance of mobile applications, it’s essential that you keep the code as light and compact as possible. Keeping codes small would reduce the latency and increase the speed.

Another method to optimize the app performance is by shrinking and diminishing various JS files into one.


  1. Avoid unwanted loops

Looping in JavaScript is not considered as a good thing since it puts extra strain on the browser. It’s important to note that you do less work in the loop. The lesser work you do in the loop the faster it will make your loop. Moreover, there are some simple tricks, one of which is storing an array’s length in a different variable instead of reading the length at each iteration of the loop. This could go a long way to optimize your code and run things in a more efficient manner.


  1. Event Delegation implementation

Event Delegation makes it easier to use a single event handler which helps in efficient management of a type of event for the entire page. In the absence of Event Delegation, large web applications can stop due to the presence of several event handlers. Event Delegation comes with many perks such as: less functionality to manage, less memory required to process, and fewer ties between DOM and code.


  1. Minimize DOM Access

Interaction of the host browser with objects (DOM) that takes place outside the JavaScript native environment results in a significant amount of performance lag and unpredictability. This occurs since the browser has to refresh every time. To avoid this, you can simply minimize the access of DOM. There are a few ways by which you achieve this. For example, you can store references to the browser objects or you can decrease the overall DOM traversal trips.


  1. Specify the execution context

To develop a website using JavaScript, you must define an environment where you can test the performance of the code and thus effectively measure any noticeable improvements which you’re planning to incorporate in the program.


Performing tests for all versions of JavaScript engine is not advisable due to feasibility issues. However, it doesn’t mean that you should test it in a single environment as it may give partial results. Therefore, it becomes essential to define several well-defined environments to test whether the code works on them or not.


  1. Get rid of unused JavaScript

This method is known for reducing the time taken by the browser to compile the code. This also reduces the transmission time. To get rid of unused JavaScript, you must consider several points such as detecting functionality which is not being used by any of the users. This enables the website to load faster along with providing better user experience.


  1. Use tools that detect problems

Lighthouse is a tool widely used for web pages. It helps in accessibility, audit performance, SEO, and other best practices. Similarly, Google PageSpeed is built to help JavaScript developers to understand areas of improvement and performance optimizations of a website.

In Chrome\’s main menu, there’s an option of ‘More Tools’ which shows you the memory and the CPU usage by each tab. 


  1. Implement the various optimizations

To solve all the tasks with optimal data structures, you must always use the algorithms that have the least complexity.


a.Get the same results with fewer calculations by rewriting algorithms.

b.Avert recursive calls

c.Put in calculations, calls, and variables for all the repeated functions

d.Simplify mathematical formulas

e.Use search arrays to get a value which is based on another rather than that of a case

f.statement or a switch.

g.Take advantage of speculative execution of processors by creating conditions that are likely to be true.



In this blog we tried to provide you with top 11 tips that can improve the JavaScript performance and help you to provide the latest JavaScript development services. The above tips will provide a very small performance boost. However, if they all are implemented together then you’ll witness a huge improvement in the speeds of your JavaScript web development and applications.

You may face difficulty in memorizing all these tips at one go and especially when you’re working under a deadline. However, with time and practice, you’ll learn all these techniques and see a significant improvement in your JavaScript performance.

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