Mathias Bynens

About me

Hi there! I’m Mathias. I work on Chrome at Google. HTML, CSS, JavaScript, Unicode, performance, and security get me excited. You can follow me on Twitter, Bluesky, and GitHub.

Latest notes

A horrifying globalThis polyfill in universal JavaScript

Published · tagged with JavaScript

The globalThis proposal introduces a unified mechanism to access the so-called “global object” a.k.a. “the global” in any JavaScript environment. It sounds like a simple thing to polyfill, but it turns out it’s pretty hard to get right.

Continue reading “A horrifying globalThis polyfill in universal JavaScript”…

JavaScript engine fundamentals: optimizing prototypes

Published · tagged with JavaScript, performance

This article explains JavaScript engine optimization pipeline trade-offs, and describes how engines such as V8 speed up accesses to prototype properties. As a JavaScript developer, having a deeper understanding of how JavaScript engines work helps you reason about the performance characteristics of your code.

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JavaScript engine fundamentals: Shapes and Inline Caches

Published · tagged with JavaScript, performance

This article describes some key fundamentals that are common to all JavaScript engines — and not just V8, the engine the authors work on. As a JavaScript developer, having a deeper understanding of how JavaScript engines work helps you reason about the performance characteristics of your code.

Continue reading “JavaScript engine fundamentals: Shapes and Inline Caches”…

Asynchronous stack traces: why await beats Promise#then()

Published · tagged with JavaScript, performance

Compared to using promises directly, not only can async and await make code more readable for developers — they enable some interesting optimizations in JavaScript engines, too! This write-up is about one such optimization involving stack traces for asynchronous code.

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ECMAScript regular expressions are getting better!

Published · tagged with JavaScript, Unicode

This article highlights what’s happening in the world of JavaScript regular expressions right now. Spoiler: it’s quite a lot — there are more RegExp-related proposals currently advancing through the TC39 standardization process than there have been updates to RegExp in the history of ECMAScript!

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