js提交验证

function validate() { var usernameValue=document.getElementById("usernameId"); var passwordValue=document.getElementById("password"); var repasswordValue=document.getElementById("repassword"); alert("validate()"); if(usernameValue.length==0) { alert("111111111111"); alert("username should not be blank!"); return false; } else if(usernameValue.length<6||usernameValue.length>10) { alert("length of username should be between 6 and 10!"); return false; } if(passwordValue.length==0) { alert("password should not be blank!"); return false; } else if(passwordValue.length<6||passwordValue.length>10) { alert("length of password should be between 6 and 10!"); return false; } if(repasswordValue.length==0) { alert("repassword should not be blank!"); return false; } else if(repasswordValue.length<6||repasswordValue.length>10) { alert("length of repassword should be between 6 and 10!"); return false; } return true; }

    ............................

..................

...................
不管输入的用户名长度是否符合要求长度，都会提交。
请帮忙看下什么地方不对呢。我用的是MEclipse 7.5

[code="java"]var usernameValue=document.getElementById("usernameId");

if(usernameValue.length==0)
{
alert("111111111111");
alert("username should not be blank!");
return false;
}
else if(usernameValue.length10)
{

alert("length of username should be between 6 and 10!");
return false;
} [/code]
usernameValue =document.getElementById("usernameId");这个只是获取一个对象
所以usernameValue.value.length就OK了.