Adds an event handler that runs when playback is started or restarted.
An element can be played by a user clicking the gallery or slideshow's
play button or by calling its play() function.
Notes:
When using onPlay() on a gallery, make sure the
gallery is one where the isPlayable
capability is true.
If you change a gallery's type
to one that doesn't support onPlay(), your code may no longer function correctly.
handler(event: Event): void The name of the function or
the function expression to run when the element is played.
This method doesn’t return any custom errors, but may return standard errors. Learn more about standard Wix errors.