$.extend($.expr[':'], {
    over100pixels: function(a) {
        return $(a).height() > 100;
    }
});

$('.box:over100pixels').click(function() {
    alert('The element you clicked is over 100 pixels high');
});

http://www.tvidesign.co.uk/blog/improve-your-jquery-25-excellent-tips.aspx#tip15

Create custom jQuery selector

jquery

JavaScript