<script type='text/javascript' language="javascript">
function validate()
    {
        var error=0;
        var name=document.getElementById("name");
        var checkname =/^[a-zA-Z]+$/;
        var email= document.getElementById("email");
        var emailcheck = /^([a-zA-Z0-9_.-])+@([a-zA-Z0-9_.-])+\.([a-zA-Z])+([a-zA-Z])+/;
        var re_pass;


        if (name.value == "") {
            name.style.background = 'Yellow'; 
            error = 1;
            alert('enter user name!');
        } else if ((name.value.length < 5) || (name.value.length > 15)) {
            name.style.background = 'Yellow'; 
            error = 1;
            alert('name must be between 5 and 15 characters!');
        } else if (!checkname.test(name.value)) {
            name.style.background = 'Yellow'; 
            error = 1;
            alert('invalid name! must be alphabet!');
        } else {
            name.style.background = 'White';
        }


        if (email.value == "") {
            email.style.background = 'Yellow'; 
            error = 1;
            alert('enter email address!');
        } else if (!emailcheck.test(email.value)) {
            email.style.background = 'Yellow'; 
            error = 1;
            alert('invalid email address!');
        } else {
            email.style.background = 'White';
        }

        if (pass.value == "") {
            pass.style.background = 'Yellow';
            error =1;
            alert('enter your passward!');
        } else if ((pass.value.length < 4) || (fld.value.length > 15)) {
            pass.style.background = 'Yellow';
            error = 1;
            alert('passwerd  must be between 4 and 15 characters!');
        }

        if (re_pass.value == "") {
            re_pass.style.background = 'Yellow';
            error = 1;
            alert('enter your passward again!');
        }
        else if(pass.value!=re_pass.value){
            re_pass.style.background="yellow!";
            error=1;
            alert('both passward must be same!');
        }
        if(error=1)
            return false;
            else
            return true;
    }
</script>Inline Code Example Here

thas my code. the problem is that the validation errors alert occur but form is also submitted either it is validated or not

First, line 61 is a typo: '=' is not a comparison, but rather an assignment. But whether or not it's correct, are you sure your calling function is interpreting the false return correctly?