一些浏览器的屏蔽功能

http://www.putiancheng.com/tool/parent.html

document.onkeydown = function(){
	//屏蔽[Alt+←]、[Alt+→]
	if (window.event.altKey && (window.event.keyCode == 37 || window.event.keyCode == 39)){
		//alert("不准你使用ALT+方向键前进或后退网页！");
		event.returnValue = false;
	}
	//屏蔽[退格删除键](event.keyCode == 8 || )、[F5]、[F11]、[Ctrl+R]
	if (event.keyCode == 116 || event.keyCode == 122 || (event.ctrlKey && event.keyCode == 82)){
		event.keyCode = 0;
		event.returnValue = false;
	}
	//屏蔽[Ctrl+n]
	if (event.ctrlKey && event.keyCode == 78)event.returnValue=false;
	//屏蔽[shift+F10]
	if (event.shiftKey && event.keyCode == 121)event.returnValue=false;
	//屏蔽[shift 加鼠标左键新开一网页]
	if (window.event.srcElement.tagName == "A" && window.event.shiftKey)window.event.returnValue = false;
	//屏蔽[Alt+F4]
	if (window.event.altKey && window.event.keyCode == 115){
		window.showModelessDialog("about:blank","","dialogWidth:1px;dialogheight:1px");
		return false;
	}
}
document.oncontextmenu = function(){
	//屏蔽鼠标右键
	event.returnValue = false;
}
window.onhelp = function(){
	//屏蔽F1帮助
	return false;
}