jQuery: finding previous div

Question

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<div class="a" style="display:none">Content 1</div>
<div class="a" style="display:none">Content 2</div>

some other HTML...

<span id="b">foobar</span>

How can I match the first div class="a" above the span id="b" to show() it? The id="b" is the only thing I know before.

Answer 1

Like this:

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$('#b').prevAll('.a:first').show();

Answer 2

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$("#b").closest(".a").show();

Try that.