javascript performance test

Tips for Javascript Perfomance Testing

Andreea Zorz Developer Tips, Tricks & Resources

No user likes to spend time waiting for a web page to load. No web developer likes a website or app to fail either. It’s important to focus on creating quick loading pages with error-free code.  JavaScript is used to build the majority of the dynamic, real-time applications. JavaScript’s strength is in the context of apps that update content dynamically with minimal latency. JavaScript performance testing should be a priority for ensuring a good end user experience and optimal performance. Here are some useful tips that can help you with performance testing.


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Tips For Performance Testing

Get Rid Of Unused JavaScript

Getting rid of unused JavaScript reduces transmission time. Moreover, it also cuts the browser code compiling time. It’s not difficult to achieve this. All you need to do is remove the functionality that your users no longer use and remove all the JavaScript code associated with it. This will cleanse the clutter resulting in quicker loading time.

Check for functionalities that already come with a browser so that you can remove any unnecessary or extra code. Most of the time extra code means additional loading time. 

Don’t Use Too Much Memory

Limit memory usage as much as possible because you don’t know how much memory the user’s device needs to load your webpage or run your application. Utilizing the browser’s garbage collector will lead to JavaScript stopping and  slower loading time.

Avoid Memory Leaks

If there is a memory leak, the web page continues to reserve more memory. Ultimately, this decreases the occupancy of the device’s entire memory and impacts performance.This is most likely in the case of a web page that has an image gallery or slider.

It is important to check for memory leaks and fix the issue to avoid overloading the user’s device and creating a bad user experience.

Use Web Workers For Time Consuming Code

Web Workers allow processor intensive calculations without any blockage to the UI thread. For efficient performance, Web Workers let you create new threads. You can delegate work so that long running tasks that cause a backlog can now be passed to a worker. This boosts performance and allows for a seamless user experience.

Implement Various Optimizations

Just like in any other language or framework, use optimizations for best results. JavaScript performance testing is all about getting the best output in order to have a UX that keeps your users coming back to you.

  • Rewrite algorithms wherever necessary to achieve the same results with lesser calculations.
  • Simplify mathematical formulas as much as possible.
  • Replace some operations with bit-level operators as they use lesser processor cycles.
  • Use calls to functions and variables that can be repeated.

Use Application Performance Management Tools

It is important to use an application performance management tool when it comes to JavaScript performance testing. 

Chrome allows you to use the “More Tools” option to check the memory and CPU usage by each tab. You can also go for an advanced analysis by using the developer tools performance view in Chrome or Firefox to analyse various metrics.

Application Performance Management tools like Retrace come with Real User Monitoring (RUM).  RUM accelerates web performances by allowing you to monitor front end and back end code together.  This more comprehensive perspective makes identifying bottlenecks easier and better pinpoints the correct solution. As website performance is optimized, web pages respond quicker and feel more interactive. End-users are happy, become more engaged, and ultimately, are more likely to buy.

RUM includes resource breakdowns to quickly help you identify if your images need to be optimized or if your stylesheets and scripts need to be minified or cached. RUM’s segmentation functionality allows for deeper insights. Use segmentation to monitor load times based on browser, geography, and device type. This makes it easy to identify opportunities to improve the overall experience by pinpointing optimal locations for CDNs.  Try your free, 14 day Retrace RUM trial today. 

The Balance Between Readability and Optimization

While JavaScript performance is very important, you also need to make sure that you pay equal attention to adding new functionalities and detecting errors.

A successful website or app is dependent on good code, great performance and detailed performance testing. Make sure that you take care of all of these three aspects well with an application performance management tool, like Stackify Retrace.