injector is property
Angular injector subsystem is in charge of creating components, resolving their dependencies, and providing them to other components as requested.
Dependency Injection (DI) is a software design pattern that deals with how components get hold of their dependencies.The Angular injector subsystem is in charge of creating components, resolving their dependencies, and providing them to other components as requested.
https://docs.angularjs.org/guide/di
An injector is a service locator. It is used to retrieve object instances as defined by provider, instantiate types, invoke methods and load modules. There is a single injector per Angular application, it helps to look up an object instance by its name.