javascript - Should I use single quotation mark or double to describe jquery?

I'm
confusing what I should use in jQuery.
Some use single some use double
quotation mark.
For
example

$('.class1').removeClass('class1')
$(".class1").removeClass("class1")

Also,
alert as
well

alert("aa");
alert('aa');

which
one is correct?

itemprop="text">

class="normal">Answer

This is
more a matter of preference than correctness. See this question for more details: href="https://stackoverflow.com/questions/242813/when-to-use-double-or-single-quotes-in-javascript">When
to use double or single quotes in JavaScript?