JavaScript Insert Tabs into Textarea; Insert Tabs Into Input; Javascript Tab Indent

<textarea cols="50" id="mytextarea" rows="15"></textarea>

$(document).ready(function(){
    $('#mytextarea').keydown(
        function(e){
            if(this.setSelectionRange){
                var start=this.selectionStart,val=$(this).val();
                switch(e.keyCode){
                    case 9: /* tab */
                        $(this).val(val.substring(0,start)+'t'+val.substr(this.selectionEnd));
                        this.setSelectionRange(start+2,start+2);
                        this.focus();
                        e.preventDefault();
                        return false;
                        break;
                    case 13: /* enter */
                        var match=val.substring(0,start).match(/(^|n)([ t]*)([^n]*)$/);
                        if(match){
                            var spaces=match[2],length=spaces.length+1;
                            $(this).val(val.substring(0,start)+'n'+spaces+val.substr(this.selectionEnd));
                            this.setSelectionRange(start+length,start+length);
                            this.focus();
                            return false;
                        }
                        break;
                }
                return true;
            }
        }
    );
});