Type Alias CmcdTransformRequest<C>

The media request passed to a report transform, as a read-only view.

The request is context only. A transform reads it to decide what to do with the report. A transform must not mutate the request, which belongs to the caller and may still be in use. Every member is readonly, and customData is readonly at every depth, so nested values cannot be written either.

By default customData values are unknown rather than any, because the library cannot know the player's fields. Narrow with a cast or bracket access to read player-specific fields:

transform: (data, request) =>
	request?.customData?.['requestType'] === 'segment' ? data : null
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Supply C to describe the player's own customData instead, and those reads become typed dot access. Annotating one transform is enough: the reporter infers C for every other transform in the same configuration.

type PlayerData = { requestType: string; };

const segmentsOnly: CmcdEventReportTransform<PlayerData> = (data, request) =>
	request?.customData?.requestType === 'segment' ? data : null
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This type wraps C in DeepReadonly, so a nested C keeps both the read-only guarantee and typed reads.

Two limits apply. A mutable body such as FormData or URLSearchParams has mutating methods of its own that no type can block. JavaScript callers get no enforcement at all. Both kinds of mutation are unsupported, and the outgoing report may reflect them.