Apple's UK site billboard resizing JavaScript

var HeroResize=AC.Class({initialize:function(b){this._height=null;this._hero=$(b);
AC.Object.synthesize(this);this.__boundResizeHero=this.resizeHero.bindAsEventListener(this);
if(typeof window.ontouchstart==="undefined"){this.resizeHero();Event.observe(window,"resize",this.__boundResizeHero)
}},setHeight:function(b){this._height=(b<0)?0:b;return this._height},resizeHero:function(){this.setHeight(parseInt(window.innerHeight||(window.document.documentElement.clientHeight||window.document.body.clientHeight),10)-310);
this.hero().style.height=this.height()+"px"}});Event.onDOMReady(function(){var b=new HeroResize("billboard")
});