javascript helpers

generators.js

/* how to iterate a object  */

post = {title: 'New features in JS', replies: 19}

post[Symbol.iterator] = function *() {
  let properties = Object.keys(this)
  for (let p of properties) {
    yield this[p]
  }
}

for (let p of post) {
  console.log(p)
}

isThisActuallyNumberDontLie.js

/* is this value a number */

function isThisActuallyNumberDontLie (data) {
  return (typeof data === 'number' && !isNaN(data))
}

ripple.md

const position = this.getBoundingClientRect()
const midX = position.left + position.width * 0.5
const midY = position.top + position.height * 0.5

const rX = Math.max(midX, window.innerWidth - midX)
const rY = Math.max(midX, window.innerHeght - midY)

const radius = Math.sqrt(rX * rX + rY * rY)

domElm.style.width = `${radius * 2}px`
domElm.style.height = `${radius * 2}px`

SpeedTest.js

/* test functions speed  */

class SpeedTest {
  constructor (testImplement, testParams, repetitions = 10000) {
    this.testImplement = testImplement
    this.testParams = testParams
    this.repetitions = repetitions
    this.average = 0
  }
  
  speedTest () {
    if (this.testImplement(this.testParams) === false) {
      alert('Test failed with those parameters.')
      return
    }
    let beginTime, endTime, sumTimes = 0
    for (let i = 0, x = this.repetitions; i < x; i++) {
      beginTime = +new Date()
      this.testImprement(this.testParams)
      endTime = +new Date()
      sumTimes += endTime - beginTime
    }
    this.average = sumTimes / this.repetitions
    return console.log(`Average execution across ${this.repetitions}: ${this.average}`)
  }
}