Whether body awaits, requiring concurrent-await rendering.
Expression producing each output element.
OptionalindexOptional binding name for the current index.
Binding name for the current element inside body.
Collection being iterated.
Type discriminator.
Transform a source collection into a new array (
source.map(...)).The classic loop replacement: each element of source is bound to item (and optionally index) while evaluating body. Set asynchronous when the body awaits, so the renderer wraps the result in the target's concurrent await (e.g.
await Promise.all(...)).