I have a validation script that checks for data-* attributes to determine which fields are required. If an element has the 'data-required-if' attribute (which has a jQuery selector as it's value), it checks to see if any elements are found that match that selector. If any are found, the field is required. It does something similar to the following:

$('[data-required-if]').each(function () {
  var selector = $(this).attr('data-required-if'),
      required = false;

  if ( !$(selector).length ) {
    required = true;
    // do something if this element is empty
  }
});

This works great, but there's a problem. When you use the attribute selector to filter based on the current value of a text field, it really filters on the initial value of the text field.

<input
  type='text'
  id='myinput'
  value='initial text'
/>

<input
  type='text'
  id='dependent_input'
  value=''
  data-required-if="#myinput[value='']"
/>

// Step 1: type "foobar" in #myinput
// Step 2: run these lines of code:
<script>
  $('#myinput').val()                  //=> returns "foobar"
  $('#myinput[value="foobar"]').length //=> returns 0
</script>

I understand why it's doing that. jQuery probably uses getAttribute() in the background. Is there any other way to filter based on the current value of an input box using purely jQuery selectors?