Optimized: Using A JavaScript (JS) Profiler For Improved Performance

Elizabeth Hines Developer Tips, Tricks & Resources

No matter what you’re coding, there’s always room to optimize your code and improve performance. This can be a painstaking process, and if you’re going over your code line by line you’d better cancel all your plans and forget about getting any sleep! Fortunately, there are better ways to examine and optimize your code. A JS profiler is an efficient tool to help you understand your code better – effectively finding, pinpointing and optimizing bottlenecks in your code. 

They’re simple to run once you get used to the interface and it’s likely you even have one built into your browser. Let’s take a closer look at these powerful tools – a JS profiler is the coder’s best friend.

Defining High Performance

There are two factors that determine your website’s performance. The first is how fast your site loads. This is crucial for keeping end users engaged. On the web you’ve got around five seconds before somebody’s attention is diverted elsewhere – so you want your site to be loading fast.

Secondly, your site’s performance depends on the code. Sluggish code, even once your site’s loaded, will alienate visitors with faulty icons and lagging interactive elements. Optimizing your code is vital to your website’s performance as it  can impact everything from customer satisfaction to lead generation, conversions, and revenue. Your code is at the heart of your website and it affects everything that users are interacting with day-to-day. To provide a seamless user experience, you need to optimize your code so that it’s up to scratch.

JS Profiling

There are a number of JavaScript profilers you can use to analyse and optimize your code. The easiest one to get started with is Google’s own profiler, which is integrated with Chrome.. You’ll find Chrome’s JS profiler under More Tools>More Developer Tools.  You can also access it through the keypad shortcut Ctrl+Shift+I. Once you’ve opened this in-browser pop-up, navigate to Performance in the tabs.

It was helpful of Google to integrate a JS profiler into your browser – it means you can profile and optimize your code on the go. However, there’s limited functionality within Chrome’s profiler so we’ll also explore some other options on the market. Retrace, for example, has tons of great features that can be tried out on their free trial.

A Performance Baseline

The first thing you need to do is to establish a baseline level of performance.  This provides  the opportunity to examine your code and how it functions. To determine your baseline performance, open the Timeline tab and click on record, then reload your page. Chrome will record your page’s loading process and the time it took to load. You can repeat this process a few times and average the loading time.  Often loading times will be boosted in later loads, as more information is cached in your browser, so it’s important not to take the first timeline as a given.

This timeline gives you a starting point – you’ll see exactly how your code is performing as well as a valuable breakdown of particular functions which are eating up the most loading time. This is where you can start optimizing.

Utilizing The JS Profiler

Chrome’s Timeline will provide you with vital information about your code’s performance.  To get to the heart of performance issues, you’ll need the profiler proper. 

Stackify’s Application Performance Management tool, Retrace, includes Real User Monitoring (RUM) to monitor JavaScript Applications. RUM is a way of monitoring the client side portions of an application. Real User Monitoring for JavaScript allows developers to have access to key metrics for load times and user paths being used in production as part of APM. 

Real User Monitoring also helps pinpoint issues that were not identified in staging due to the restrictions of pre-production testing and different platforms used in production. With the RUM data collected, developers can proactively address and prioritize solutions to slow running JavaScript and keep users happy.

Real User Monitoring for JavaScript collects key metrics like load times, errors, and platform incompatibility. Page specific monitoring allows for developers and product managers to see where and when there are slow load times for JavaScript elements that negatively impact the customers and where improvements can be made to enrich the user experience. 

Download your FREE, two week Retrace trial to explore RUM.

Streamlining The Solution

Busy code is a lot harder to optimize.  Once you’ve identified problematic functions through Retrace Real User Monitoring, isolating these will help you identify bottlenecks and improve performance. 

There are a number of easy tweaks you can make to improve your code’s performance. Improving jQuery selection by improving the specificity of your selectors tends to lead to solid performance gains. Separating out certain selectors can also enable your code to run faster – especially with regards to :visible, :hidden and :focus.

When optimizing your code, the profiler will list your functions by CPU usage. For an efficient process of optimization, start with the slowest pieces of code first – this is where you’ll make the greatest performance gains. There’s almost always a subtle tweak to speed up your code.

Wrapping Up

Coding can be a labour of love and it’s easy to want to wash your hands of it once you’ve built a functional website. But optimizing your code is a vital step that speeds up your site and ensures your users are having a great experience interacting with your icons and design. Without optimized code, you could be turning away customers and losing revenue. JS Profilers make optimization easy – simply follow the steps above to explore an in depth analysis of your code. You’ll have whip-sharp code in no time.

About Elizabeth Hines

Elizabeth Hines is a tech writer and avid coder at Top Canadian Writers and Study demic. She writes about emerging tech trends and is fluent in Java and Python. You can read more of her work at Academized Review.