How to select children elements but only one level deep with jQuery

Question

Given this:

<div id="div1">
    <div id="div2">
        <div id="div200">
            <div id="div3" class="b">       
            </div>
            <div id="div300">
                <div id="div4" class="b">
                     <div id="div5"> 
                        <div id="div6" class="b">
                        </div>            
                     </div>
                </div>
            <div>
        <div>
    <div>
</div>

I need a way to find the children (deep) of an element that are of class "b" but not those that are nested inside a matched element.

Test cases:

This is what I need:

Case 1:

$("#div1").some_jquery_syntax(".b")
Should return:
div3, div4

Case 2:

$("#div5").some_jquery_syntax(".b")
Should return:
div6

Note that the hard part is that I have have to skip div2 when starting from div1. So I can't just use $("#div1").find("> .b").

My attempts:

I tried this:

$("#div1").find(".b")
[<div id="div3" class="b"></div>, <div id="div4" class="b"></div>, <div id="div5" class="b"></div>]

Not good: I don't want div5 because it is nested inside div4.

I tried this:

$("#div0").find(".b").not(".b .b")
[<div id="div3" class="b"></div>, <div id="div4" class="b"></div>]

Which is ok when starting with div0, but it does not work stating from div4:

$("#div5").find(".b").not(".b .b")
[]

Answer 1

Find the immediate grand-children:

​$("#div1").children().children(".b");

Fiddle: http://jsfiddle.net/jonathansampson/Dy6GJ/

If you don't know how deep to go, but want all .b not within a .b, use a filter while respecting parent limitations. You could use the .parentsUntil method:

var parent = "#div1";
$(".b", parent).filter(function(){
    return !$(this).parentsUntil(parent, ".b").length;
}).css("border", "1px solid red");​​​​​​​​​​​​​​​​​

Fiddle: http://jsfiddle.net/jonathansampson/Dy6GJ/3/

Answer 2

General (when only class can be guaranteed):

$("#div1").find(".b:not(.b .b)")

As described (likely faster than general, though not tested):

$("#div1").find("div.b:not(div.b div.b)")

"All .b which are not descendants of .b"