When we think of learning Dependency Injection in Angular, couple of questions arises like
- How this DI concept works in Angular?
- What are all the important components that make it work?
This video 0008-12- angular: Dependency Injection (DI) Token part 1/3 will help you to get answers for most of your queries. It makes you understand
- What that core component is?
- Why it is required?
- What exactly it does?
This component is known as DI Token (Dependency Injection Token) which is nothing but a key part in key-value pair similar to a lookup key which does lookup in lookup table.
E.g. If there is class A needs class B as dependency, so in order to know where that B instance exist and to get that & give it to Class A, angular need some identifier that name or key to find/identify the instance of B is known DI Token.
So in simple words we can define DI Token as a key to lookup for instance of the dependencies and it has to be valid at run time.