Count elements with jQuery

$('.someclass').length

You could also use:

$('.someclass').size()

.size() is now removed as of jQuery 3.0.

var count_elements = $('.class').length;

From: http://api.jquery.com/size/

The .size() method is functionally equivalent to the .length property; however, the .length property is preferred because it does not have the overhead of a function call.

Please see:

http://api.jquery.com/size/

http://api.jquery.com/length/