getEnd functions for a TweenData based on a target property and end value.
getActive if not null, is invoked immediately as soon as the TweenData is running, and is set on the target property.
getEnd is invoked once any start delays have expired and returns what the value should tween to.
getStart is invoked when the tween reaches the end and needs to either repeat or yoyo, it returns the value to go back to.
If the end value is a number, it will be treated as an absolute value and the property will be tweened to it.
A string can be provided to specify a relative end value which consists of an operation
+= to add to the current value,
-= to subtract from the current value,
*= to multiply the current
/= to divide the current value) followed by its operand.
A function can be provided to allow greater control over the end value; it will receive the target object being tweened, the name of the property being tweened, and the current value of the property as its arguments.
If both the starting and the ending values need to be controlled, an object with
callbacks, which will receive the same arguments, can be provided instead. If an object with a
property is provided, the property will be used as the effective value under the same rules described here.
The name of the property to modify.
The ending value of the property, as described above.
An array of functions,
getEnd, which return the starting and the ending value of the property based on the provided value.