代码一：

<script type="text/javascript">   
function password() {   
var testV = 1;   
var pass1 = prompt('请输入密码','');   
while (testV < 3) {   
if (!pass1)   
history.go(-1);   
if (pass1 == "123") {//初始密码123   
alert('密码正确!');   
break;   
}   
testV+=1;   
var pass1 =   
prompt('密码错误!请重新输入:');   
}   
if (pass1!="password" & testV ==3)   
history.go(-1);   
return " ";   
}   
document.write(password());   
</script>

代码二：

<script type="text/javascript">   
function password() {   
var testV = 1;   
var pass1 = prompt('Sorry,该页只限熟人浏览,请输入密码:','');   
while (testV < 3) {   
if (!pass1)    
history.go(-1);   
if (pass1 == "123") {//初始密码123   
alert('一看你就是自己人，口令正确!');   
window.location.href="http://www.xiaokuangyl.com";//修改需要密码认证的网页   
break;   
}    
testV+=1;   
var pass1 =    
prompt('朋友，密码不对！:(','');   
}   
if (pass1!="password" & testV ==3)    
history.go(-1);   
return " ";   
}    
document.write(password());   
</script>

友情提示：如果你把这段JS代码放在新建的页面里，请把JS代码加密