Introspecting the Decorated Class

Once a class is decorated with Angular decorators like @Component, @Pipe, @Directive, and so on, Angular can read the metadata to figure out what to do with them.

In our example, where we simulated the Angular @Component decorator, we stored the properties given to the decorator into the metadata.

Verification by example

Let’s verify that the decoration actually worked.

Explanation

• We import SampleComponent and query for its metadata keys by calling Reflect.getMetadataKeys(); this method is added to the Reflect class by the reflect-metadata library that we imported earlier.

• Then we obtain the metadata for the annotations ...