function addLoadEvent(func){

	var oldonload = window.onload;
	
	if(typeof window.onload != 'function'){
	
		window.onload = func;
		
	} else {
	
		window.onload = function(){
		if(oldonload){
			oldonload();
		}
		func();
		}
		
	}
}


addLoadEvent(slider);