slikts

React context vs Redux in 2020

The [React docs][condoc] give some example use cases for context:

Context is designed to share data that can be considered “global” for a tree of React components, such as the current authenticated user, theme, or preferred language.

The common property of these use cases is that data like the current theme doesn't change often and needs to be shared deep down the component tree, which would be cumbersome with "[prop drilling][drill]". Something else that needs to be shared everywhere is the application state when using a "single source of truth" pattern, so it would follow that the context API would help with that as well, but there's a catch: components that use context will rerender every time that the provided value changes, so sharing the whole application state through context would cause excessive render lifecycles.

slikts

Advanced memoization and effects in React

Memoization is a somewhat fraught topic in the React world, meaning that it's easy to go wrong with it, for example, by [making memo() do nothing][memo-pitfall] by passing in children to a component. The general advice is to avoid memoization until the profiler tells you to optimize, but not all use cases are general, and even in the general use case you can find tricky nuances.

Discussing this topic requires some groundwork about the technical terms, and I'm placing these in once place so that it's easy to skim and skip over:

• Memoization means caching the output based on the input; in the case of functions, it means caching the return value based on the arguments.
• Values and references are unfortunately overloaded terms that can refer to the low-level implementation details of assignments in a language like C++, for example, or to memory

bvaughn

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
  • Create React App
  • Webpack 4

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.

david206

Data from [https://snowflake.medium.com/]

Engineering growth: tracks

Table of Contents

• Mobile
  • Works effectively within established iOS or Android architectures, following current best practices
  • Develops new instances of existing architecture, or minor improvements to existing architecture
• Designs major new features and demonstrates a nuanced understanding of mobile platform constraints

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.

---

Effective Engineer - Notes

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

What's an Effective Engineer?

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

kentcdodds

Angular Snippets

Some snippets for Chrome that I've made or found/modified and thought were useful.

dergachev

OS X Screencast to animated GIF

This gist shows how to create a GIF screencast using only free OS X tools: QuickTime, ffmpeg, and gifsicle.

Instructions

To capture the video (filesize: 19MB), using the free "QuickTime Player" application:

michaelcox

require.config({
  baseUrl: '/backbone-tests/',
  paths: {
    'jquery'        : '/app/libs/jquery',
    'underscore'    : '/app/libs/underscore',
    'backbone'      : '/app/libs/backbone',
    'mocha'         : 'libs/mocha',
    'chai'          : 'libs/chai',
    'chai-jquery'   : 'libs/chai-jquery',
    'models'        : '/app/models'

chetan

YARD CHEATSHEET http://yardoc.org

May 2020 - updated fork: https://gist.github.com/phansch/db18a595d2f5f1ef16646af72fe1fb0e

cribbed from http://pastebin.com/xgzeAmBn

Templates to remind you of the options and formatting for the different types of objects you might want to document using YARD.

Modules