sindresorhus

Pure ESM package

The package that linked you here is now pure ESM. It cannot be require()'d from CommonJS.

This means you have the following choices:

1. Use ESM yourself. (preferred)
   Use import foo from 'foo' instead of const foo = require('foo') to import the package. You also need to put "type": "module" in your package.json and more. Follow the below guide.
2. If the package is used in an async context, you could use await import(…) from CommonJS instead of require(…).
3. Stay on the existing version of the package until you can move to ESM.

una

CSS Color Functions

Web developers and design systems developers often use functions to design components. With the increasing usage of design systems that support multiple platforms, and increased capability of Dark Mode in UI, this becomes even more useful to not need to manually set color, and to instead have a single source from which layouts are calculated. Currently Sass, calc() on HSL values, or PostCSS is used to do this.

Examples:

• Components with color variations based on calculations from a parent. (i.e. Button with outline that uses the primary button color to adjust the size)
• Theming - Palletes based on a color or set of colors for themes. Especially when a single base system is used with multiple themes
• Uniformity among transformations between components with different primary colors

Proposal

bvaughn

React recently introduced an experimental profiler API. This page gives instructions on how to use this API in a production release of your app.

Table of Contents

• Profiling in production
  • Create React App
  • Webpack 4

Profiling in production

React DOM automatically supports profiling in development mode for v16.5+, but since profiling adds some small additional overhead it is opt-in for production mode. This gist explains how to opt-in.

samthor

// UPDATE: In 2023, you should probably stop using this! The narrow version of Safari that
// does not support `nomodule` is probably not being used anywhere. The code below is left
// for posterity.

/**
 * Safari 10.1 supports modules, but does not support the `nomodule` attribute - it will
 * load <script nomodule> anyway. This snippet solve this problem, but only for script
 * tags that load external code, e.g.: <script nomodule src="nomodule.js"></script>
 *
 * Again: this will **not** prevent inline script, e.g.:

addyosmani

Problem: How can we preprocess JavaScript (at build-time or on the server-side) so engines like V8 don't have to spend as much time in Parse? This is a topic that involves generating either bytecode or a bytecode-like-abstraction that an engine would need to accept. For folks that don't know, modern web apps typically spend a lot longer in Parsing & Compiling JS than you may think.

• Yoav: This can particularly be an issue on mobile. Same files getting parsed all the time for users. Theoretically if we moved the parsing work to the server-side, we would have to worry about it less.
• One angle to this problem is we all ship too much JavaScript. That's one perspective. We could also look at preprocessing.
• We've been talking about this topic over the last few weeks a bit with V8. There were three main options proposed.
• 1. Similar to what optimize-js does. Identify IIFEs and mark them as such so the browser and VMs heuristics will catch them and do a better job than today. optimize-js only tackles IIFE bu

jlongster

A lot of people mentioned other immutable JS libraries after reading my post. I thought it would be good to make a list of available ones.

There are two types of immutable libraries: simple helpers for copying JavaScript objects, and actual persistent data structure implementations. My post generally analyzed the tradeoffs between both kinds of libraries and everything applies to the below libraries in either category.

Libraries are sorted by github popularity.

Persistent Data Structures w/structural sharing

paulirish

What forces layout / reflow

All of the below properties or methods, when requested/called in JavaScript, will trigger the browser to synchronously calculate the style and layout*. This is also called reflow or layout thrashing, and is common performance bottleneck.

Generally, all APIs that synchronously provide layout metrics will trigger forced reflow / layout. Read on for additional cases and details.

Element APIs

Getting box metrics

• elem.offsetLeft, elem.offsetTop, elem.offsetWidth, elem.offsetHeight, elem.offsetParent

sergejmueller

Prolog

Google Chrome Developers says:

The new WOFF 2.0 Web Font compression format offers a 30% average gain over WOFF 1.0 (up to 50%+ in some cases). WOFF 2.0 is available since Chrome 36 and Opera 23.

Some examples of file size differences: WOFF vs. WOFF2

TTF to WOFF2 converting

• http://www.fontsquirrel.com/tools/webfont-generator

chenglou

Interesting part (unmounting & API) is at the end if you're not interested in the rest =).

Stress Tests

This animation proposal is just an attempt. In case it doesn't work out, I've gathered a few examples that can test the power of a future animation system.

1. Parent is an infinitely spinning ball, and has a child ball that is also spinning. Clicking on the parent causes child to reverse spinning direction. This tests the ability of the animation system to compose animation, not in the sense of applying multiple interpolations to one or more variables passed onto the child (this should be trivial), but in the sense that the parent's constantly updating at the same time as the child, and has to ensure that it passes the animation commands correctly to it. This also tests that we can still intercept these animations (the clicking) and immediately change their configuration instead of queueing them.

2. Typing letters and let them fly in concurrently. This tests concurrency, coordination of an array of ch

branneman

Better local require() paths for Node.js

Problem

When the directory structure of your Node.js application (not library!) has some depth, you end up with a lot of annoying relative paths in your require calls like:

const Article = require('../../../../app/models/article');

Those suck for maintenance and they're ugly.

Possible solutions