These features are experimental, officially unsupported, and thus undocumented.  If you want to explore, noting in advance that there are known bugs in this functionality:

  • repeat accepts an array, and you can refer to a given member of that array (i.e. within other expressions, e.g. to make the position a function of the data in the array) using $repeat.payload.
  • if accepts a boolean value, which will toggle whether the element is rendered on the stage.
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