@searchfe/inject-js
v1.6.4
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A Dependency Injection library
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inject-js
A tiny dependency Injection library for TypeScript. https://searchfe.github.io/inject-js/
Install
Can be installed via npm
npm install --save @searchfe/inject-js
inject-js uses Reflect Metadata to determine dependencies, so you need make sure your tsconfig.json
contains:
{
"compilerOptions": {
"experimentalDecorators": true,
"emitDecoratorMetadata": true
}
}
And, you'll need a polyfill for the Reflect API, such as:
Usage
Following are some use cases, more details please refer to the API Reference.
@injectable
@injectable is used to decorate the Service class, so that its dependencies can be resolved by inject-js and it can be injected to other services.
// car.ts
import { injectable } from 'inject-js';
import { Wheel } from './wheel';
@injectable
export class Car {
constructor(private wheel: Wheel) {}
}
// wheel.ts
import { injectable } from 'inject-js';
@injectable
export class Wheel {
constructor() {}
}
// index.ts application entry
import { Container } from 'inject-js';
import { Car } from './car';
import { Wheel } from './wheel;
const di = new Container();
di.addService(Car);
di.addService(Wheel);
const car = di.create(Car);
@inject
@inject(token) is used to decorate a dependency (constructor argument) to specify which provider should be used. The token
argument is the unique identifier of a Provider within the container. token
is typically used for cases where there's no Service class actually defined, or Metadata API is not available.
import { inject } from 'inject-js';
import { Wheel } from './wheel';
@injectable
export class Car {
constructor(@inject('Wheel') private wheel: Wheel) {}
}
// index.ts application entry
import { Container } from 'inject-js';
import { Car } from './car';
import { Wheel } from './wheel';
const di = new Container();
di.addService('Wheel', Wheel);
di.addService(Car);
const car = di.create(Car);
@service
If the container instance is available in the context where Services are defined, @service can be used as a shorthand of .addService()
:
const container = new Container();
@service(container)
class FooService {}
// Equivalent to:
const container = new Container();
@injectable
class FooService {}
container.addService(FooService)
Container
The Container class maintains a set of Providers and the corresponding Tokens. There're several ways to register Providers:
- .addProvider(): register a factory class with a
.create(): Service
method. All other ways are implemented using.addProvider()
internally. - .addFactory(): register a factory function which returns a Service instance.
- .addService(): register a concrete Service class.
- .addValue(): register a value.