Im writing some logic in JavaScript using jquery, where i must check the input content against a REGEX pattern ex:

"^[a-zA-Z0-9_]*$"  //Alpha-numeric and _

The logic is almost done, i just have a little problem filtering the function key DEL, my logic goes like this:

var FunctionsKey = new Array(8, 9, 13, 16, 35, 36, 37, 39, 46);

function keypressValidation(key) {
            if (config.regexExp != null) {
                if ($.inArray(key, FunctionsKey) != -1) {
                    return true;
                }
                else {
                    var keyChar = String.fromCharCode(key);
                    return RegexCheck(keyChar);
                }
            }
            return true;
        }

If the KeyCode is one of those in the array, i let it pass, if not i get the char and compare it against the REGEX. The problem is: in some Browsers the DEL and '.' (period sign) have the same key Code 46.

So is there a better logic to filter the function keys or must i write a condition for that case, maybe removing the 46 from the array and try to convert it to char and if is (.) let it go to the Regex function if not let it pass? The other question will be are there more shared Key Codes in some browsers?

EDIT: My suggested solution wont work because it doesn't matter which key the user pressed (DEL or period) i always get (.) as CHAR at least on OPERA and FF =(.