code: function fadeIn(el)
  {
  	el.style.opacity = 0;
  	el.style.display = "block";
  
  	(function fadeIn() {
  		let val = parseFloat(el.style.opacity);
  		if (! ((val += .1) > 1)) {
  			el.style.opacity = val;
  			setTimeout(fadeIn, 40);
  		}
  	})();
  }
docs: Apply a fade in effect to a given element.
  
  @param  {Object} el
  @return {Void}