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422701 (3) [Avatar] Offline
#1
Can you explain they ?
Yakov Fain (219) [Avatar] Offline
#2
In general, metadata is an additional information about data. For example, in the MP3 file the audio is the data, but the name of the artist, song title and the album cover is metadata. The MP3 player includes the metadata processor that reads the metadata and displays them while playing the song.

In case of classes, the metadata is additional information about the class. For example, the @Component decorator (a.k.a annotation) tells Angular (the metadata processor) that this is not a regular class, but a component. Angular generates additional JavaScript code based on the information provided in properties of the decorator.

In case of class properties, the decorator @Input tells Angular that this class property should support binding and be able to receive the data from the parent component.

You can also think of a decorator as a function, that performs some actions on the decorated element.