//////////////////////////////////////////////////////////////////////
// CLib
function CLib(){
	////////////////////////////////////////////////////////////////////
	// $shorthands
	function $(selector,el_ref){
		return (el_ref?el_ref:document).querySelector(selector);
	};
	function $$(selector,el_ref){
		return (el_ref?el_ref:document).querySelectorAll(selector);
	};
	function $id(id){
		return document.getElementById(id);
	};
	function $ce(tagName){
		return document.createElement(tagName);
	};

	////////////////////////////////////////////////////////////////////
	// utils
	function emptyObject(x){
		if(x){
			if(x.constructor===Object){
				for(const key in x){delete x[key];}
			}else if(x.constructor===Array){
				x.length=0;
			}
		}
	};

	function isEmptyObject(x){
		for(const i in x){return false;}
		return true;
	};

	function isObject(x){
		return(x&&(x.constructor===Object));
	};

	////////////////////////////////////////////////////////////////////
	// end events
	function onEnd(el,callback,ename){
		const func=function(e){
			if(el==e.srcElement){
				el.removeEventListener(ename,func);
				if(callback){callback(e);}
			}
		};
		el.addEventListener(ename,func);
	};
	function onTransitionEnd(el,callback){
		onEnd(el,callback,"transitionend");
	};
	function onAnimationEnd(el,callback){
		onEnd(el,callback,"animationend");
	};
	function classDuringTransition(el,clsname,callback){
		el.offsetHeight;// for reflow
		if(el.classList.contains(clsname)){
			onTransitionEnd(el,function(e){
				el.classList.add(clsname);
				if(callback){callback(e);}
			});
			el.classList.remove(clsname);
		}else{
			onTransitionEnd(el,function(e){
				el.classList.remove(clsname);
				if(callback){callback(e);}
			});
			el.classList.add(clsname);
		}
	};
	function classDuringAnimation(el,clsname,callback){
		el.offsetHeight;// for reflow
		if(el.classList.contains(clsname)){
			onAnimationEnd(el,function(e){
				el.classList.add(clsname);
				if(callback){callback(e);}
			});
			el.classList.remove(clsname);
		}else{
			onAnimationEnd(el,function(e){
				el.classList.remove(clsname);
				if(callback){callback(e);}
			});
			el.classList.add(clsname);
		}
	};

	////////////////////////////////////////////////////////////////////
	// return
	return{
		$,
		$$,
		$ce,
		$id,
		emptyObject,
		isEmptyObject,
		isObject,
		onEnd,
		onTransitionEnd,
		onAnimationEnd,
		classDuringTransition,
		classDuringAnimation,
	};
};