anthonybrown

// createContext
const WeatherContext = React.createContext({ day: 3 })
const App = ({ children }) => {
  const [weather, setWeather] = React.useState(null)
  const [error, setError] = React.useState(null)
  React.useEffect(() => {
    api.getWeather(...)
      .then(setWeather)
      .catch(setError)
  }, [])

anthonybrown

const bigArr = new Array(1000000).fill(1).map((_, i) => i);
bigArr[100] = 5;

const allUnique = arr => {
  const all = new Set();

  for (let el of arr) {
    if (all.has(el)) {
      return false;
    }

anthonybrown

/** Store Data */
const prices = {
  game: 59.95,
  nintendo: 399.99,
  controller: 49.99,
  xbox: 299.99,
  ps1: 349.99
}

const basket = [

anthonybrown

function greetCurried(greeting) {
  return function(name) {
    if (typeof(greeting) !== 'string') {
      return ('Greetings!')
    } else if (typeof(name) !== 'string') {
      return (greeting)
    }

    return (`${greeting}, ${name}`)
  }

anthonybrown

function getAdd() {
  let foo = 0;
  return function() {
    foo = foo + 1;
    return foo;
  };
}

const add = getAdd()

anthonybrown

class Decimal {
  constructor(number) {
    this.precision = 8
    this.number = number
    this.integer = Math.floor(number)
    this.fractional = Math.round(number * Math.pow(10, this.precision))
  }
  
  [Symbol.toPrimitive](hint) {
    // hint can be: string, number, default

anthonybrown

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

anthonybrown

Terminal Cheatsheet for Mac (Basics)

Letters are shown capitalized for readability only. Capslock should be off.

SHORTCUTS

Key/Command	Description
Ctrl + A	Go to the beginning of the line you are currently typing on. This also works for most text input fields system wide. Netbeans being one exception
Ctrl + E	Go to the end of the line you are currently typing on. This also works for most text input fields system wide. Netbeans being one exception

anthonybrown

#! /usr/bin/env node
# Usage: node create-react-component.js ComponentName
# Note: If a `components` directory does not exist in the current working directory, nothing will be created

const fs = require('fs')
const path = require('path')
const componentName = process.argv[2]
const componentPath = path.join(
  'components',
  componentName

anthonybrown

Array<T>

Legend:

• ✏️ method changes this.
• 🔒 method does not change this.

Array<T>.prototype.*:

• concat(...items: Array): T[] 🔒 ^ES3