String.prototype.trim  =  function(){return  this.replace(/(^\s*)|(\s*$)/g,  "");}
function gid(id){return document.getElementById(id);}
function setTab(name,cursel,n){
for(i=1;i<=n;i++){
var menu=gid(name+i);
var con=gid("con_"+name+"_"+i);
menu.className=i==cursel?"hover":"";
con.style.display=i==cursel?"block":"none";
}
}
function checklogin(){
	if(gid("username").value.trim() == ""){
		alert("通行证不能为空");
		gid("username").focus();
		return false;
	}
	if(gid("pwd").value == ""){
		alert("密码不能为空");
		gid("pwd").focus();
		return false;
	}
	return true;
}