.css()

Get the value of a computed style property for the first element in the set of matched elements or set one or more CSS properties for every matched element.

callbacks.has()

Determine whether or not the list has any callbacks attached. If a callback is provided as an argument, determine whether it is in a list.

jQuery.each()

A generic iterator function, which can be used to seamlessly iterate over both objects and arrays. Arrays and array-like objects with a length property (such as a function’s arguments object) are iterated by numeric index, from 0 to length-1. Other objects are iterated via their named properties.