Skip to content

Instantly share code, notes, and snippets.

View danielmascena's full-sized avatar
🎯
Focusing

Daniel Mascena danielmascena

🎯
Focusing
61 followers · 327 following
View GitHub Profile
@getify
getify / 1-CalendarItem.js
Last active March 21, 2024 09:11
an illustration (non-trivial example) of many newer JS class features
// abstract class, not intended to be instantiated directly
class CalendarItem {
static #UNSET = Symbol("unset")
static #isUnset(v) {
return v === this.#UNSET;
}
static {
for (let [idx,msg] of [
"ID is already set.",
"ID is unset.",
@getify
getify / why-typl-instead-of-ts.md
Last active July 20, 2022 18:26
describing my motivations for designing TypL instead of using TS/Flow

I am often asked why I don't like a tool like TS (or Flow), and by implication, if I don't like it, the assumption is that I don't want any type aware tooling. That's not true, though.

I have many ideas for what I think type-aware tooling in JS could/should be, and they just happen to diverge significantly enough from TS/Flow that I can't bend into pretzels to fit into that mold.

Instead, I've worked on designing a tool I call TypL that I think addresses my concerns. It's in progress.

Here's my main list of motivations for designing TypL instead of TS/Flow:

  1. I want a system that has both compile-time checking AND run-time checking. TypL's design is to compile away the stuff that it checks at compile time and can verify, and leave in the stuff that it knows needs run-time checking. That way, you don't have to write different sorts of type checking for compile-time and run-time. You get both from one set of typing annotation. It doesn't really seem tha
@turicas
turicas / brasil_io.py
Last active August 13, 2022 23:04
Exemplo de código para acessar dados do Brasil.IO
import csv
import gzip
import io
import json
from urllib.parse import urlencode, urljoin
from urllib.request import Request, urlopen
class BrasilIO:
@bitfishxyz
bitfishxyz / v.js
Created May 15, 2020 00:37
const inBrowser = typeof window !== 'undefined'
const inWeex = typeof WXEnvironment !== 'undefined' && !!WXEnvironment.platform
const weexPlatform = inWeex && WXEnvironment.platform.toLowerCase()
const UA = inBrowser && window.navigator.userAgent.toLowerCase()
const isIE = UA && /msie|trident/.test(UA)
const isIE9 = UA && UA.indexOf('msie 9.0') > 0
const isEdge = UA && UA.indexOf('edge/') > 0
const isAndroid = (UA && UA.indexOf('android') > 0) || (weexPlatform === 'android')
const isIOS = (UA && /iphone|ipad|ipod|ios/.test(UA)) || (weexPlatform === 'ios')
const isChrome = UA && /chrome\/\d+/.test(UA) && !isEdge
@housecricket
housecricket / square.js
Created May 1, 2020 08:07
var square = {}
(function() {
var length = 0, width = 0
Object.defineProperty(square, "length", {
get: function() { return length },
set: function(value) { length = width = value }
})
@andywer
andywer / _readme.md
Last active March 7, 2024 05:52
React - Functional error boundaries

React - Functional error boundaries

Thanks to React hooks you have now happily turned all your classes into functional components.

Wait, all your components? Not quite. There is one thing that can still only be implemented using classes: Error boundaries.

There is just no functional equivalent for componentDidCatch and deriveStateFromError yet.

Proposed solution

@maciejtrzcinski
maciejtrzcinski / Object.is-polyfill.js
Created October 30, 2018 19:15
if (!Object.is) {
Object.is = function(x, y) {
// SameValue algorithm
if (x === y) { // Steps 1-5, 7-10
// Steps 6.b-6.e: +0 != -0
return x !== 0 || 1 / x === 1 / y;
} else {
// Step 6.a: NaN == NaN
return x !== x && y !== y;
}
@bvaughn
bvaughn / index.md
Last active April 19, 2024 04:34
How to use profiling in production mode for react-dom

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

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.

@gaearon
gaearon / index.html
Last active January 26, 2024 11:25
Add React in One Minute
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8" />
<title>Add React in One Minute</title>
</head>
<body>
<h2>Add React in One Minute</h2>
<p>This page demonstrates using React with no build tooling.</p>
@rauschma
rauschma / string.md
Last active February 5, 2024 04:12

Strings

String.prototype.*

None of the string methods modify this – they always return fresh strings.

  • charAt(pos: number): string ES1

    Returns the character at index pos, as a string (JavaScript does not have a datatype for characters). str[i] is equivalent to str.charAt(i) and more concise (caveat: may not work on old engines).