Verify if all options are selected in looks

look.html

<script type="text/javascript">
    $(document).ready(function(){
        $('#look-form').submit(function(e){
            var form = e;
            var prevented = false;
    	    $('.product-id:checked').each(function(){
    	        if($(this).prev().val() == '' && !prevented){
    	            form.preventDefault();
    	            alert('Por favor selecione todas as opções');
    	            prevented = true;
    	        }
    	    });
    	});
    });
</script>