How to use Espruino with WS2812 arrays? (Like RGB-123)

Just to add, you could also use E.toUint8Array() to prepare the array. You can do things like:

>E.toUint8Array([[1,2,3],[4,5,6],[7,8,9]])
=new Uint8Array([1, 2, 3, 4, 5, 6, 7, 8, 9])

>E.toUint8Array([{data:[1,2,3], count:4},[7,8,9]])
=new Uint8Array([1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 7, 8, 9])