jQuery Custom Expression

Here is simple example how you can provide custom expressions for jquery like :visible, :first etc.

<!DOCTYPE html>
<title>jQuery Custom Expression</title>
<meta charset="UTF-8" />

<span>Hello</span>
<span style="display:block">World</span>

<script src="http://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js"></script>
<script>
  ;(function ($) {
    $.extend($.expr[':'], {
      block: function (a, i, m) {
        return $(a).css('display') == 'block'
      }
    })
  })(jQuery)
</script>
<script>
  jQuery('span:block').hide()
</script>