Question

<div id="main">
 <div class="a"></div>
 <div class="b"><p>not me</p></div>
 <div class="b"></div>
 <div class="b"></div>
 <div class="c"></div>
</div> 

How we can write a selector to select all divs with class b except whose child is <p>not me</p> ?

Answer 1

$('div.b:not(:has(p))').........

Or the readable version

$('div.b').filter(function(){
    return !$(this).find('p').length;
});

If you want to match the content as well:

$('div.b').filter(function(){
    return $(this).find('p').text() !== "not me";
});

Live DEMO