rauschma

import assert from 'node:assert/strict';

// Extended RegExp mode (flag /x) [1] via a template tag
//
// Quote: “While the x-mode flag can be used in a RegularExpressionLiteral,
// it does not permit the use of LineTerminator in RegularExpressonLiteral.
// For multi-line regular expressions you would need to use the RegExp
// constructor.”
//
// The plan is to include this functionality in re-template-tag [2]. Then

rauschma

Better dynamic type checks

• Update 2022-07-10: new approach based on Function.prototype.hasInstance()

Problems

In principle, the rule “typeof is for primitive values, instanceof is for objects” works. There are two exceptions:

• Checking if a value is an object
• Cross-realm instance checks

rauschma

import {ReadableStream} from 'node:stream/web';

/**
 * @param iterable an iterable (asynchronous or synchronous)
 * 
 * @see https://streams.spec.whatwg.org/#example-rs-pull
 */
 function iterableToReadableStream(iterable) {
  return new ReadableStream({
    async start() {

cowboyd

/**
 * Implements an operation to fetch the data as described in https://twitter.com/BenLesh/status/1455597411385098242
 * The "winner" is unambiguous. It is the request corresponding to the latest click, guaranteed. 
 * Other important things to note:
 *
 * 1. The HTTP request is cancelled every time along with its containing task
 * 2. click listener is removed automatically at the end of the `clickToLoad` operation
 * 3. The cancellation logic is explicit here to demonstrate the concept, but it can easily be abstracted into a separate 
 *.   function. See the `click-to-load-HOF` example below
 */

aszx87410

It's the reply to the question raised by @getify on his twitter:

here's a variation on the question... will JS engines exhibit much performance difference between these two loops?

for (var i = 0; i < 100000000; i++) {
   // do some stuff, but not closure
}

for (let i = 0; i < 100000000; i++) {

WebReflection

Update

If you're OK in having a node-esm executable, please consider this solution.

#!/usr/bin/env sh
# the /usr/local/bin/node-esm executable
input_file=$1
shift
exec node --input-type=module - $@ <$input_file

MTuner

Apple removed colored sub-pixel antialiasing in MacOS Mojave
(https://developer.apple.com/videos/play/wwdc2018/209/ starting from ~28min)

To make fonts look normal in Sublime Text, add to Preferences:

// For the editor
"font_options": [ "gray_antialias" ],
// For the sidebar / other elements
"theme_font_options": [ "gray_antialias" ],

yelouafi

In this tutorial we're going to build a set of parser combinators.

What is a parser combinator?

We'll answer the above question in 2 steps.

1. What is a parser?
2. and, what is a parser combinator?

So first question: What is parser?

ggauravr

While attempting to explain JavaScript's reduce method on arrays, conceptually, I came up with the following - hopefully it's helpful; happy to tweak it if anyone has suggestions.

Intro

JavaScript Arrays have lots of built in methods on their prototype. Some of them mutate - ie, they change the underlying array in-place. Luckily, most of them do not - they instead return an entirely distinct array. Since arrays are conceptually a contiguous list of items, it helps code clarity and maintainability a lot to be able to operate on them in a "functional" way. (I'll also insist on referring to an array as a "list" - although in some languages, List is a native data type, in JS and this post, I'm referring to the concept. Everywhere I use the word "list" you can assume I'm talking about a JS Array) This means, to perform a single operation on the list as a whole ("atomically"), and to return a new list - thus making it much simpler to think about both the old list and the new one, what they contain, and

michaelficarra

function append(separator) {
  return typeof separator === "string" ? appender(separator, "") : appender("", "").apply(this, arguments);
}

function appender(separator, s) {
  return function tag(literalParts, ...computedParts) {
    s += literalParts[0];
    for (let i = 1; i < literalParts.length; ++i) {
      s += computedParts[i - 1] + literalParts[i];
    }