Vanilla Javascript .fadein() .fadeOut() without JQuery [closed]

Answer 1

This will do the trick:

function _(el) {
  if (!(this instanceof _)) {
    return new _(el);
  }
  this.el = document.getElementById(el);
}

_.prototype.fade = function fade(type, ms) {
  var isIn = type === 'in',
    opacity = isIn ? 0 : 1,
    interval = 50,
    duration = ms,
    gap = interval / duration,
    self = this;

  if(isIn) {
    self.el.style.display = 'inline';
    self.el.style.opacity = opacity;
  }

  function func() {
    opacity = isIn ? opacity + gap : opacity - gap;
    self.el.style.opacity = opacity;

    if(opacity <= 0) self.el.style.display = 'none'
    if(opacity <= 0 || opacity >= 1) window.clearInterval(fading);
  }

  var fading = window.setInterval(func, interval);
}

_('myButton').fade('out', 500);

From here on out you can extend your _ object with any jQuery-like function.