JavaScript is one of those languages that looks simple on the surface but keeps revealing new layers the deeper you go. Even developers with years of experience often discover gaps in understanding, performance blind spots, or better ways to approach familiar problems. Over time, I’ve learned that improving as a JavaScript developer isn’t about consuming endless tutorials, but about using the right tools at the right moments.
The websites in this list are not just learning platforms. They are practical companions that help you reason about JavaScript, write better code, and make smarter technical decisions in real-world projects.
JavaScript.info
When you want to truly understand how JavaScript works, not just how to use it, JavaScript.info is unmatched. It explains fundamentals like closures, prototypes, async behavior, and the event loop with clarity and depth. This is the kind of resource you return to when something feels confusing or when you want to strengthen your foundations properly.
👉 https://javascript.info
JSBench
Performance questions often lead to assumptions. JSBench removes the guesswork by letting you compare different JavaScript implementations side by side. Instead of debating which approach is faster, you can test it directly in the browser and see real results. It’s especially useful when optimizing loops, array operations, or utility functions.
👉 https://jsbench.me
Regex101
Regular expressions can be intimidating, even for experienced developers. Regex101 turns regex from a guessing game into an understandable process. It visually explains patterns, highlights matches, and helps you debug mistakes quickly. If you work with string validation, parsing, or search logic, this tool saves hours.
👉 https://regex101.com
Bundlephobia
Modern JavaScript heavily depends on third-party packages, but every dependency comes with a cost. Bundlephobia helps you check the size impact of npm packages before installing them. It’s a simple habit that leads to smaller bundles, faster load times, and better user experiences.
👉 https://bundlephobia.com
You Don’t Know JS
The You Don’t Know JS book series dives into the “why” behind JavaScript behavior. Topics like scope, closures, coercion, and async logic are explained in a way that changes how you think about the language. It’s not a quick read, but it’s one of the most valuable long-term investments a JavaScript developer can make.
👉 https://github.com/getify/You-Dont-Know-JS
Final Thoughts
Becoming better at JavaScript isn’t about memorizing syntax. It’s about understanding behavior, measuring impact, and making informed decisions. These websites won’t just teach you JavaScript. They’ll help you think like a better developer every time you write code.