rondy

FWIW: I (@rondy) am not the creator of the content shared here, which is an excerpt from Edmond Lau's book. I simply copied and pasted it from another location and saved it as a personal note, before it gained popularity on news.ycombinator.com. Unfortunately, I cannot recall the exact origin of the original source, nor was I able to find the author's name, so I am can't provide the appropriate credits.

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Effective Engineer - Notes

• By Edmond Lau
• Highly Recommended 👍
• http://www.theeffectiveengineer.com/

What's an Effective Engineer?

bterlson

Pattern Matching

This is a strawman proposal for adding pattern matching to ECMAScript. Pattern matching is useful for matching a value to some structure in a similar way to destructuring. The primary difference between destructuring and pattern matching are the use cases involved - destructuring is useful for binding pieces out of larger structures whereas pattern matching is useful for mapping a value's structure to data or a set of behaviors. In practice this means that destructuring tends to allow many shapes of data and will do its best to bind something out of it, whereas pattern matching will tend to be more conservative.

Additionally, the power of pattern matching is increased substantially when values are allowed to participate in the pattern matching semantics as a matcher as well as a matchee. This proposal includes the notion of a pattern matching protocol - a symbol method that can be implemented by objects that enables developers to use those values in pattern matching. A common scenario w

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

domenic

// This event emitter emits events, but reserves the right to publish events to
// for its creator. It uses a WeakMap for true encapsulation.

const eesToEventMaps = new WeakMap();

export default class EventEmitter {
    constructor(publisher) {
        const eventMap = Object.create(null);
        eesToEventMaps.set(this, eventMap);

nakamura-to

// see http://d.hatena.ne.jp/ashigeru/20090113/1231855642

var calc = {
  add: function (node) {
    return visit(this, node.l) + visit(this, node.r);
  },
  sub: function (node) {
    return visit(this, node.l) - visit(this, node.r);
  },
  val: function (node) {