How to implement jQuery to get elements by class name?

Question

There is no "getElementsByClass" function in javascript,

then how to do jQuery?

Cycling all elements will be less efficient.

By the way, how to specify css for elements with two or more classes?

<a class="one two">test</a>

Guess how down below?

.one.two {...}

Is it correct?

Answer 1

The getElementsByClassName function exists, jQuery uses it internally, if available, check the selector.js file in the jQuery source

To select items with multiple classes, use the .class.class selector:

$('.one.two')

Answer 2

jQuery Sizzle.