Javascript validation.html

<html>
<head>
    <title> title of the </title>
    <script type="text/javascript">
        function validate()
        {
            var name=document.getElementById ("name").value;
            var username=document.getElementById("username").value;
            var reusername=document.getElementById("reuserame").value;
            var password=document.getElementById("passsword").value;
            var age=document.getElementById("age").value;
            var email=document.getElementById("email").value;
            var atpos=email.lastindexof("@").value;
            var dotpos=email.lastindexof(".").value;
            if (name=="// name.length<1")
        {
            document.write("Name is empty");
            return false;
        }
        if (username==""|| Username.length<1)
{
    document.write ("username is empty");
    return false;
}
if (username!=reusername)
{
    document.write ("username & reusername is not same");
    return false;
}
if (password=""||password.length<6)
{
    document.write("password is less than 6 characters");
    return false;
}
if (age=="" || is (age))
{
    document.write ("Age is not a number");
    return false;
}
if (atpos<2 ||(dotpos-atpos)<2)
{
    document.write ("email format is not correct");
    return false;
}
}
</script>
</head>
<body>
    <form method ="POST">
        </form>
        </body>
        </html>
    