[jQuery] Select class="class1 class2" using jQuery

[jQuery] Select class="class1 class2" using jQuery


I need to select an element like this:
<div class="class_1 class_a"></div>
and I've found that both of the following work:
$(".class_a").filter(".class_1").css("background-color", "red");
$(".class_a.class_1").css("background-color", "red");
The first one makes sense and is documented on the website. But the
second one isn't documented anywhere as far as I can tell.
My question is this: is this, i.e.
$(".class_a.class_1")
intended, documented behavior or is this some fluke that is likely to
disappear? Is there a URL where this behavior is documented? I would
like to use the second selector syntax (i.e., $(".class_a.class_1") )
but don't want to rely on it if it's likely to disappear.
Thanks!