Answers for "display button when input is not empty jquery"

jquery check if input is empty on submit

var empty = true;
$('input[type="text"]').each(function() {
   if ($(this).val() != "") {
      empty = false;
      return false;
   }
});

jquery select input with empty value

$('input:text').filter(function() { return $(this).val() == ""; });