Skip to content

Instantly share code, notes, and snippets.

View Cfeusier's full-sized avatar

Clark Feusier Cfeusier

View GitHub Profile
var str = 'class ಠ_ಠ extends Array {constructor(j = "a", ...c) {const q = (({u: e}) => {return { [`s${c}`]: Symbol(j) };})({});super(j, q, ...c);}}' +
'new Promise((f) => {const a = function* (){return "\u{20BB7}".match(/./u)[0].length === 2 || true;};for (let vre of a()) {' +
'const [uw, as, he, re] = [new Set(), new WeakSet(), new Map(), new WeakMap()];break;}f(new Proxy({}, {get: (han, h) => h in han ? han[h] ' +
': "42".repeat(0o10)}));}).then(bi => new ಠ_ಠ(bi.rd));';
try {
eval(str);
} catch(e) {
alert('Your browser does not support ES6!')
}
@pygy
pygy / cancelPromise.md
Last active May 9, 2024 13:27
You can already cancel ES6 Promises

The gist: by having a Promise adopt the state of a forever pending one, you can suspend its then handlers chain.

Promise.pending = Promise.race.bind(Promise, [])

let cancel

new Promise(function(fulfill, reject) {
  cancel = function() {fulfill(Promise.pending())}
  setTimeout(fulfill, 1000, 5)
@Rich-Harris
Rich-Harris / module-loading.md
Last active April 19, 2023 09:11
Dynamic module loading done right

Dynamic module loading done right

Follow-up to Top-level await is a footgun – maybe read that first

Here are some things I believe to be true:

  1. Static module syntax is beneficial in lots of ways – code is easier to write (you get better linting etc) and easier to optimise (tree-shaking and other things that are only really possible with static syntax), and most importantly, faster to load (it's trivial for a module loader to load multiple dependencies concurrently when they're declared with a static syntax – not so with imperative statements like require(...) or await import(...)).
  2. App startup time is perhaps when performance is most critical. (You already know this, I don't need to cite the studies.)
  3. If you're in favour of constructs that jeopardise app startup time, you are anti-user. Top-level await is such a construct.
@dmvaldman
dmvaldman / promisesEM.md
Last active June 1, 2024 00:20
Promises as EventEmitters

Promises as EventEmitters

I was trying to understand JavaScript Promises by using various libraries (bluebird, when, Q) and other async approaches.

I read the spec, some blog posts, and looked through some code. I learned how to

@paulirish
paulirish / what-forces-layout.md
Last active September 23, 2024 11:37
What forces layout/reflow. The comprehensive list.

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
@brock
brock / nodereinstall.sh
Last active August 28, 2024 21:19
Complete Node Reinstall. I've moved this to a repo at http://git.io/node-reinstall
#!/bin/bash
# node-reinstall
# credit: http://stackoverflow.com/a/11178106/2083544
## program version
VERSION="0.0.13"
## path prefix
PREFIX="${PREFIX:-/usr/local}"
@staltz
staltz / introrx.md
Last active September 20, 2024 10:10
The introduction to Reactive Programming you've been missing