Paypal add to cart button form ignores the "return false" and submits. This script works on a desktop browser but it won't work on my iPhone. The input turns red, but the form still submits. It can be tested at membership form
$('input[name="submit"]').click(function() {
$(':input').each(function(input) {
    if($(this).attr('required')) {
        var required = $(this);
        if(required.attr('pattern')) {
            var patt =  new RegExp(required.attr('pattern'),"i");
            if( !patt.test( required.val() ) ) {
                required.css('background-color','#f2dede');
                return false;
            }
        }
        else {
            if(required.val() == '') {
                required.css('background-color','#f2dede');
                return false;
            }
        }
    }
});
				
                        
By placing an "e" in the function(e) for the event, and then use e.preventDefault() I was able to keep the form from submitting.