Previously, we discussed website performance issues related to CSS and HTML. Now, let’s look at JavaScript and identify different problems that occur on websites and how you can monitor them before end-users are affected.


If you’re lucky, you can identify the problem and troubleshoot right away. If you don’t yet know what you’re dealing with, you could start here:

Server performance: Momentary server hiccups may result in incomplete code being sent to the browser.

Issues with third-party sites: If you query a third-party site without having it load asynchronously, you will likely have JavaScript issues on your site.

Corrupt cache file: This can cause unstable application performance and random error messages that pop up in the browser. Sometimes it can even make the application crash.

Outdated files: The browser might be using an outdated version of one or more JavaScript files from its cache.

Browser compatibility: Many times, JavaScript features work differently in different browsers.

JavaScript code: There could be a genuine error in the JavaScript code itself. For example, a missing semicolon or brackets, comments within comments, or code with missing statements such as return, throw, break, etc.

Others possible issues: The scripting engine, video card drivers, or Direct X controls could be corrupt or outdated.


5 Tips to Monitor JavaScript

1. Test Web pages in the development stage. When you’re building the website, you can monitor the logic of the code by recording transactions that involve JavaScript code and verifying their functionality.

2. Match images. If you have JavaScript menus and complex features on the page, you can use text and image matching to simply validate that the page is displayed as you intended.

3. Monitor load times. Establish an ideal baseline for how long it should take for your application to load. Then monitor the load times of each step in the page. If a step loads slowly, you’ll then receive an alert about the problem in the page or step.

4. Look at browser compatibility. Make sure you do QA testing on multiple browsers to ensure JavaScript has the desired effect on all browsers your application supports.


5. Monitor JavaScript performance. All of your page elements turned out perfectly, but you can tell some of the elements are slow to load. Monitor those sluggish elements so you know whether JavaScript was the real culprit. It could be other elements such as CSS, HTML, DNS Lookup, etc. at the root cause.




                              Monitor individual page elements to identify what is causing the issue


Monitor JavaScript Issues Using Web Performance Monitor

When in doubt, rely on Web performance monitoring software to keep an eye on JavaScript along with other front-end applications such as HTML, CSS, Images, and third-party applications. SolarWinds Web Performance Monitor proactively monitors your webpages and alerts you to any change in the way your sites or elements within them look or renders. Web Performance Monitor also offers:

• Intuitive charts to monitor page elements, their load speeds & timings

• A graphical dashboard that monitors every component of your site

• Drill-down capabilities & isolation of performance issues to quickly determine what’s causing the delay

• JavaScript performance monitoring for multiple locations, to ensure consistent user experience

• Customized alerts based on the severity level