typewriter.js

const typeWriter = (el, cb) => {
  const TxtType = function(config) {
    this.type = config.type
    this.el = config.el
    this.speed = config.speed
    this.txt = ''
    this.i = 0
    this.tick()
  }
  TxtType.prototype.tick = function() {
    const fullTxt = this.type
    const charCount = fullTxt.length
    const that = this
    let delta = this.speed - Math.random() * 200
    this.txt = fullTxt.substring(0, this.txt.length + 1)
    this.el.innerHTML = `<span>${this.txt}</span>`
    setTimeout(function() {
      if ( that.i < charCount ) {
        that.i ++
        that.tick()
      } else {
        cb()
      }
    }, delta)
  }
  // Initialze
  const type = el.getAttribute('data-type')
  const speed = el.getAttribute('data-speed')
  el.innerHTML = `<span></span>`
  if (type) {
    new TxtType({
      el: el,
      type: type,
      speed: speed
    })
  }
}

export default typeWriter