Skip to content

Instantly share code, notes, and snippets.

View ar5had's full-sized avatar
🎯
Focusing

Arshad Khan ar5had

🎯
Focusing
View GitHub Profile
@azurite
azurite / deepCopy.js
Last active March 11, 2017 18:57
Quick and dirty way to deep copy json objects in javascript (object prototypes are not copied)
function isNull(v) {
return typeof v === "object" && !v;
}
function isPrimitive(v) {
return ["number", "string", "boolean", "undefined"].indexOf(typeof v) !== -1 || isNull(v);
}
function isPlainObject(o) {
return o && typeof o === "object" && o.constructor === Object;
@ca0v
ca0v / debounce.ts
Last active April 4, 2024 08:28
Typescript Debounce
// ts 3.6x
function debounce<T extends Function>(cb: T, wait = 20) {
let h = 0;
let callable = (...args: any) => {
clearTimeout(h);
h = setTimeout(() => cb(...args), wait);
};
return <T>(<any>callable);
}

Parens And Performance

Years ago, some smart folks that worked on JS engines realized that not all JS that's loaded into a page/app initially is needed right away. They implemented JIT to optimize this situation.

JIT means Just-In-Time, which means essentially that the engine can defer processing (parsing, compiling) certain parts of a JS program until a later time, for example when the function in question is actually needed. This deferral means the engine is freer to spend the important cycles right now on the code that's going to run right now. This is a really good thing for JS performance.

Some time later, some JS engine devs realized that they needed to get some hints from the code as to which functions would run right away, and which ones wouldn't. In technical speak, these hints are called heuristics.

So they realized that one very common pattern for knowing that a function was going to run right away is if the first character before the function keyword was a (, because that usually m

@brianmacarthur
brianmacarthur / flash-app.js
Last active July 10, 2023 18:41
Flash messaging in Express 4: express-flash vs. custom middleware in ejs, handlebars, or jade
var express = require('express');
var cookieParser = require('cookie-parser');
var session = require('express-session');
var flash = require('express-flash');
var handlebars = require('express-handlebars')
var app = express();
var sessionStore = new session.MemoryStore;
// View Engines
@adam-p
adam-p / Local PR test and merge.md
Last active February 5, 2024 19:39
Testing a pull request, then merging locally; and avoiding TOCTOU

It's not immediately obvious how to pull down the code for a PR and test it locally. But it's pretty easy. (This assumes you have a remote for the main repo named upstream.)

Getting the PR code

  1. Make note of the PR number. For example, Rod's latest is PR #37: Psiphon-Labs/psiphon-tunnel-core#37

  2. Fetch the PR's pseudo-branch (or bookmark or rev pointer whatever the word is), and give it a local branch name. Here we'll name it pr37:

$ git fetch upstream pull/37/head:pr37
@xem
xem / codegolf.md
Last active March 22, 2024 15:41
JS code golfing

codegolf JS

Mini projects by Maxime Euzière (xem), subzey, Martin Kleppe (aemkei), Mathieu Henri (p01), Litterallylara, Tommy Hodgins (innovati), Veu(beke), Anders Kaare, Keith Clark, Addy Osmani, bburky, rlauck, cmoreau, maettig, thiemowmde, ilesinge, adlq, solinca, xen_the,...

(For more info and other projects, visit http://xem.github.io)

(Official Slack room: http://jsgolf.club / join us on http://register.jsgolf.club)

@piscisaureus
piscisaureus / pr.md
Created August 13, 2012 16:12
Checkout github pull requests locally

Locate the section for your github remote in the .git/config file. It looks like this:

[remote "origin"]
	fetch = +refs/heads/*:refs/remotes/origin/*
	url = git@github.com:joyent/node.git

Now add the line fetch = +refs/pull/*/head:refs/remotes/origin/pr/* to this section. Obviously, change the github url to match your project's URL. It ends up looking like this:

@jasonrhodes
jasonrhodes / getProperty.js
Created April 6, 2012 17:40
Get a nested object property by passing a dot notation string as the property name
/**
* A function to take a string written in dot notation style, and use it to
* find a nested object property inside of an object.
*
* Useful in a plugin or module that accepts a JSON array of objects, but
* you want to let the user specify where to find various bits of data
* inside of each custom object instead of forcing a standardized
* property list.
*
* @param String nested A dot notation style parameter reference (ie "urls.small")
@paulirish
paulirish / rAF.js
Last active March 22, 2024 00:00
requestAnimationFrame polyfill
// http://paulirish.com/2011/requestanimationframe-for-smart-animating/
// http://my.opera.com/emoller/blog/2011/12/20/requestanimationframe-for-smart-er-animating
// requestAnimationFrame polyfill by Erik Möller. fixes from Paul Irish and Tino Zijdel
// MIT license
(function() {
var lastTime = 0;
var vendors = ['ms', 'moz', 'webkit', 'o'];