gistfile1.js

slideshow.prototype.pauseOnHover = function(){
  this.el.addEventListener('mouseover', this.pause.bind(this));
  this.el.addEventListener('mouseout', this.play.bind(this));
}

slideshow.prototype.pause = function(){
  this.paused = true;
}

slideshow.prototype.play = function(){
  this.paused = false;
}

slideshow.prototype.auto = function(speed){
  var self = this;

  if( speed == null ) {
    return this.speed !== 0; // Boolean, is it automatic?
  }

  this.speed = speed;

  // clear any previous timeouts
  if( this._timeout ) clearTimeout(this._timeout);

  // This will keep firing until the speed is set to 0.
  // If the slideshow is paused, the timeout will continue
  // but it won't move to the next slide.
  this._timeout = setTimeout(function tick(){
    if(this.speed === 0) return; // No more automatic sliding
    self._timeout = setTimeout(tick, speed); // Set it so we can clear it
    if(this.paused === false) self.next(); // Next slide if not paused
  }, speed);
}