Type guard to check if a plot publishes point-level highlight identity.
The shape is checked, not merely the name: the sibling guards above assert
typeof … === 'function' on the member they test, and the equivalent here is
that the member reads as an array. Reading it is safe and cheap — the getter
is pure over fields fixed at construction — and a trace that happened to
carry a same-named property of another shape would otherwise be fed to a
consumer expecting indices.
Type guard to check if a plot publishes point-level highlight identity.
The shape is checked, not merely the name: the sibling guards above assert
typeof … === 'function'on the member they test, and the equivalent here is that the member reads as an array. Reading it is safe and cheap — the getter is pure over fields fixed at construction — and a trace that happened to carry a same-named property of another shape would otherwise be fed to a consumer expecting indices.