Breaking a promise

July 4, 2024 By Mark Otto Off

How to Annul Promises in JavaScript — You can ‘cancel’ XHR and fetch requests, but can you cancel regular promises? Currently, no, but Zachary looks into doing the next best thing: telling a promise the game’s up, and discarding/ignoring its eventual results.

Zachary Lee

regex 2.1: Turn JavaScript’s Regular Expression Support Up to Eleven — From the co-author of O’Reilly’s High Performance JavaScript and Regular Expressions Cookbook comes an enhancement for JavaScript’s regex support. Supporting all of ES2024’s regex functionality, it adds support for free spacing and comments, atomic groups, regex subroutines, context-aware interpolation of RegExp instances, and more.

Steven Levithan

💡 The author also tells us a Babel plugin for regex is expected to be released later today.

📒 Articles & Tutorials

Enhancing The New York Times‘ Web Performance with React 18 — Last year, The New York Times set out to take full advantage of React 18 on its flagship news site. This is a tour of the challenges faced in upgrading, coupled with the significant benefits they managed to take advantage of.

Ilya Gurevich (NYT)

How We Tamed Node.js Event Loop Lag — Node famously uses very few threads yet can handle a large number of clients performantly, as long as the work associated with each client is ‘small.’ When that work isn’t ‘small’, as here, things can go off the rails quickly.

Eric Allam

A Set of Modern Web Performance Guides — A helpful collection of guides, covering things such as working with the different core web vitals, JavaScript optimization, metrics, and more.


🛠 Code & Tools

BWIP-JS: A Barcode Writer in Pure JavaScript — A library that can generate barcodes using over 100 different barcode types and standards, both single and two dimensional. There is, of course, a live demo where you, too, can discover far more types of barcodes exist than you ever imagined.

Mark Warren

🎁 And one for fun

Sliderland: A Minimalist Coding Playground — A slider control based visualization you can code with simple formulas. We last linked to this a few years ago, but it’s still a fun way to do some quick, visual JS math experimentation. is along similar lines, but based on a 2D grid.