Block registration spam bot using jquery html

THIS SCRIPT DISABLE SUBMIT BUTTON IF THE HIDDEN FORM TEXT AREA IS AUTO FILLED BY BOT

<script src='http://code.jquery.com/jquery-1.7.1.min.js'></script>
<input type="text" id="message" style="display:none;">
                <input class="button" name="adduser" type="submit" id="adduser" value="{NUSRREGNM17}">

<SCRIPT>
$(document).ready(function(){
    $('#adduser').attr('disabled',false);
    
    $('#message').keyup(function(){
        if($(this).val().length !=0){
            $('#adduser').attr('disabled', true);
        }
        else
        {
            $('#adduser').attr('disabled', false);        
        }
    })
});
</script>