Here is a fiddle to start - http://jsfiddle.net/zuVpx/1/

Javascript code:

<script>

    function validate(e) {

        var regex = new RegExp([a-zA-Z0-9]);

        var key = e.keyCode || e.which;

        key = String.fromCharCode(key);



        if(!regex.test(key)) {

            e.returnValue = false;

            if(e.preventDefault) {

                e.preventDefault();

            }

        }

    }

</script>

HTML code:

<input type=text onkeypress=validate(event) />

I want only characters and numbers. Keys like backspace, delete, capslock and arrowkeys etc should work.

Thanks in advance.