Arrow functions

1hello.md

This is code from an episode of Fun Fun Function: https://youtu.be/6sQDTgOqh-I

2events.js

const dragonEvents = [
  { type: 'attack', value: 12, target: 'player-dorkman' },
  { type: 'yawn', value: 40 },
  { type: 'eat', target: 'horse' },
  { type: 'attack', value: 23, target: 'player-fluffykins' },
  { type: 'attack', value: 12, target: 'player-dorkman' },
]

3vanilla.js

const totalDamageOnDorkman = dragonEvents
  .filter(function (event) {
    return event.type === 'attack'
  })
  .filter(function (event) {
    return event.target === 'player-dorkman'
  })
  .map(function(event) {
    return event.value
  })
  .reduce(function(prev, value) {
    return (prev || 0) + value
  })

4arrow-breakout.js

// I like the bit where he creates re-usable functions

const reduceTotal = (prev, x) => (prev || 0) + x
const isAttack = e => e.type === 'attack'

const totalDamageOnDorkman = dragonEvents
  .filter(isAttack)
  .filter(e => e.target === 'player-dorkman')
  .map(e => e.value)
  .reduce(reduceTotal)

4arrow.js

const totalDamageOnDorkman = dragonEvents
  .filter(e => e.type === 'attack')
  .filter(e => e.target === 'player-dorkman')
  .map(e => e.value)
  .reduce((prev, x) => (prev || 0) + x)