.data()

Store arbitrary data associated with the matched elements or return the value at the named data store for the first element in the set of matched elements.

jQuery.cssHooks

Hook directly into jQuery to override how particular CSS properties are retrieved or set, normalize CSS property naming, or create custom properties.

jQuery.cssNumber

An object containing all CSS properties that may be used without a unit. Prior to jQuery 4.0, the .css() method uses this object to see if it may append px to unitless values.

jQuery.data()

Store arbitrary data associated with the specified element and/or return the value that was set.