An array of animation step objects.

• When steps are defined by style() or animate() function calls, each call within the group is executed instantly.
• To specify offset styles to be applied at a later time, define steps with keyframes(), or use animate() calls with a delay value. For example:

group([
  animate("1s", style({ background: "black" })),
  animate("2s", style({ color: "white" }))
])

An options object containing a delay and developer-defined parameters that provide styling defaults and can be overridden on invocation.

Optional. Default is null.