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

The MIT License (MIT)

Copyright © <year> <copyright holders>

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

bvaughn

// This is an advanced example! It is not typically required for application code.
// If you are using a library like Redux or MobX, use the container component provided by that library.
// If you are authoring such a library, use the technique shown below.

// This example shows how to safely update subscriptions in response to props changes.
// In this case, it is important to wait until `componentDidUpdate` before removing a subscription.
// In the event that a render is cancelled before being committed, this will prevent us from unsubscribing prematurely.

// We also need to be careful about how we handle events that are dispatched in between
// `getDerivedStateFromProps` and `componentDidUpdate` so that we don't put stale values into the `state`.

TheLarkInn

const chalk = require("chalk");
const { performance } = require("perf_hooks");
class ProfilingPlugin {
  apply(compiler) {
    // Compiler Hooks
    Object.keys(compiler.hooks).forEach(hookName => {
      compiler.hooks[hookName].intercept(makeInterceptorFor("Compiler")(hookName))
    });

    Object.keys(compiler.resolverFactory.hooks).forEach(hookName => {

addyosmani

Problem: How can we preprocess JavaScript (at build-time or on the server-side) so engines like V8 don't have to spend as much time in Parse? This is a topic that involves generating either bytecode or a bytecode-like-abstraction that an engine would need to accept. For folks that don't know, modern web apps typically spend a lot longer in Parsing & Compiling JS than you may think.

• Yoav: This can particularly be an issue on mobile. Same files getting parsed all the time for users. Theoretically if we moved the parsing work to the server-side, we would have to worry about it less.
• One angle to this problem is we all ship too much JavaScript. That's one perspective. We could also look at preprocessing.
• We've been talking about this topic over the last few weeks a bit with V8. There were three main options proposed.
• 1. Similar to what optimize-js does. Identify IIFEs and mark them as such so the browser and VMs heuristics will catch them and do a better job than today. optimize-js only tackles IIFE bu

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?

btroncone

Comprehensive Introduction to @ngrx/store

By: @BTroncone

Also check out my lesson @ngrx/store in 10 minutes on egghead.io!

Update: Non-middleware examples have been updated to ngrx/store v2. More coming soon!

Table of Contents

gaearon

function mapValues(obj, fn) {
  return Object.keys(obj).reduce((result, key) => {
    result[key] = fn(obj[key], key);
    return result;
  }, {});
}

function pick(obj, fn) {
  return Object.keys(obj).reduce((result, key) => {
    if (fn(obj[key])) {

acdlite

/**
 * Basic proof of concept.
 * - Hot reloadable
 * - Stateless stores
 * - Stores and action creators interoperable with Redux.
 */

import React, { Component } from 'react';

export default function dispatch(store, atom, action) {

lancejpollard

Copied from http://code.lancepollard.com/complete-list-of-html-meta-tags/

Basic HTML Meta Tags

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