js 小demo

/**
 * 屏蔽F5
 */
function onkeydown(){
	if (event.keyCode==116){
		event.keyCode = 0;
		event.cancelBubble = true;
		return false;
	}
}
document.onkeydown = this.onkeydown;
/**
 * 屏蔽鼠标右键 
 */
function norightclick() {
	window.event.returnValue=false; 
}
document.oncontextmenu = this.norightclick;

if(self.location != top.location) {
  top.location = self.location ;
}
function isIE6(){
String.prototype.inc=function(k1,k2){return k2==null?this.indexOf(k1)>-1?true:false:(k2+this+k2).indexOf(k2+k1+k2)>-1?true:false}

var agent=navigator.userAgent
var isIE,isIE4,isIE5,isIE6,isOpr,isMoz

isOpr=agent.inc("Opera")
isIE=agent.inc("IE")&&!isOpr
isIE4=agent.inc("IE 4")
isIE5=agent.inc("IE 5")||agent.inc("IE 4")
isIE6=isIE&&!isIE5
isMoz=agent.inc("Mozilla")&&!isOpr&&!isIE

if(!isIE6){
   alert("建议您使用IE6.0、IE7.0或IE8.0的浏览器进行报名！");
}

}