OptionalemitOptionallegacyEnables experimental support for decorators, which is a version of decorators that predates the TC39 standardization process.
Decorators are a language feature which hasn’t yet been fully ratified into the JavaScript specification. This means that the implementation version in TypeScript may differ from the implementation in JavaScript when it it decided by TC39.
Enables emitting decorator metadata.
This option the same as emitDecoratorMetadata in TypeScript, and it only works when
legacyis true.