Enable submit button only when all fields are filled

Question

In my form, I want to enable form only when all fields (and radio button list) has been selected.

So far, I have successfully made the submit button enable

Answer 1

yet another solution

required = function(fields) {
  var valid = true;
  fields.each(function () { // iterate all
    var $this = $(this);
    if (($this.is(':checkbox') && !$this.is(":checked")) || // checkbox
       (($this.is(':text') || $this.is('textarea')) && !$this.val()) || // text 
       ($this.is(':radio') && !$('input[name='+ $this.attr("name") +']:checked').length)) {
            valid = false;
        }
    });
    return valid;
}

validateRealTime = function () {
    var fields = $("form :input:not(:hidden)"); // select required
    fields.on('keyup change keypress blur', function () {
        if (required(fields)) {
            {subnewtopic.disabled = false} // action if all valid
        } else {
            {subnewtopic.disabled = true} // action if not valid
        }
    });
}

http://jsfiddle.net/jsq7m8hL/2/