Function: isFocusWithin(domElement)

Description: Determines if an element currently has focus within the specified container element.

Returns: True if yes, False otherwise.

Note: The isFocusWithin() function always returns a Boolean value, even when chained.

Example:

var hasFocusWithin = $A.isFocusWithin(domElement);

// Or the same using chaining

var hasFocusWithin = $A(domElement).isFocusWithin();