Slow-loading assets on your web pages can lead to frustrated users, high bounce rates, and lost conversions. For the vast majority of websites, slow-loading resources will be your main performance bottleneck. There’s no way to get around going through the network for essential resources like JavaScript, CSS, and images — thus, it’s crucial that you can quickly identify and fix your slow-loading assets.

Monitoring and observing application performance is a cornerstone for maintaining robust and efficient systems in the ever-evolving development landscape. One key player in this domain is OpenTelemetry. This post provides a comprehensive tutorial and unpacks what OpenTelemetry is, its applications and integration into the JavaScript ecosystem.

TrackJS is the best frontend error monitoring tool. It’s all we do and we do it well. To keep it simple we have just two different JavaScript agents. One for the browser, and one for Node server environments. That’s it. No other languages or platforms are supported. Just JavaScript.

Your images are 404ing all over the place. You’ve got an angry email from a client. Their site is “broken”, images aren’t loading, cumulative layout shift is running riot, and everything is messed up. The crowds are mocking your broken code on Twitter. A fun GIF loaded via a Giphy URL no longer exists. And someone has accidentally deleted an image from the CMS.

Javascript has been enabling browsers for years, and for better or for worse, the internet is made of JS. NodeJS brought it to the server side. TypeScript has wrapped familiar object-oriented, statically-typed syntax around it. Anywhere you look, you’ll find Javascript: on the client, server, mobile, and embedded systems.

The world’s biggest language comes with a huge collection of conventions and guidelines from the community’s collective wisdom. Following JavaScript best practices can help achieve faster page loads and better performance, improve code readability, and make maintenance and debugging easier. Carefully crafted code can also prevent errors and security issues, especially if it’s complemented with real-time diagnostic tools such as JavaScript error monitoring.

Table of contents Frankly, end-to-end testing and synthetic monitoring are challenging in today’s JavaScript-heavy world. There’s so much asynchronous JavaScript code running in modern applications that getting tests stable can be a real headscratcher. That’s why many teams rely on testing mission-critical features and treat “testing the rest” as a nice to have. It’s a typical cost-effort decision.