Key

export class Key

exported from angular2/core defined in angular2/src/core/di/key.ts (line 6)

A unique object used for retrieving items from the Injector.

Keys have:

• a system-wide unique id.
• a token.

Key is used internally by Injector because its system-wide unique id allows the injector to store created objects in a more efficient way.

Key should not be created directly. Injector creates keys automatically when resolving providers.