js屏蔽瀏覽器右鍵菜單,粘貼,復制,剪切,選中

<script type="text/javascript">
//屏蔽右鍵菜單
document.oncontextmenu = function (event){
	if(window.event){
		event = window.event;
	}try{
		var the = event.srcElement;
		if (!((the.tagName == "INPUT" && the.type.toLowerCase() == "text") || the.tagName == "TEXTAREA")){
			return false;
		}
		return true;
	}catch (e){
		return false; 
	} 
}

//屏蔽粘貼
document.onpaste = function (event){
	if(window.event){
		event = window.event;
	}try{
		var the = event.srcElement;
		if (!((the.tagName == "INPUT" && the.type.toLowerCase() == "text") || the.tagName == "TEXTAREA")){
			return false;
		}
		return true;
	}catch (e){
		return false;
	}
}

//屏蔽復制
document.oncopy = function (event){
	if(window.event){
		event = window.event;
	}try{
		var the = event.srcElement;
		if(!((the.tagName == "INPUT" && the.type.toLowerCase() == "text") || the.tagName == "TEXTAREA")){
			return false;
		}
		return true;
	}catch (e){
		return false;
	}
}

//屏蔽剪切
document.oncut = function (event){
	if(window.event){
		event = window.event;
	}try{
		var the = event.srcElement;
		if(!((the.tagName == "INPUT" && the.type.toLowerCase() == "text") || the.tagName == "TEXTAREA")){
			return false;
		}
		return true;
	}catch (e){
		return false;
	}
}

//屏蔽選中
document.onselectstart = function (event){
	if(window.event){
		event = window.event;
	}try{
		var the = event.srcElement;
		if (!((the.tagName == "INPUT" && the.type.toLowerCase() == "text") || the.tagName == "TEXTAREA")){
			return false;
		}
		return true;
	} catch (e) {
		return false;
	}
}
</script>