Angular类似的Java服务依赖注入

Question

I am writing a Javascript npm package. In my code I have a single class which I want to act like an angular service. Only one instance of that class should be created and needs to be shared wherever wanted in the project.

//this class object would be shared across project and only one object can be created. also, its implementation could change in future
export class SharedClass {
    constructor(somethingImp) {
    }
    //more methods
}

export class ProjectClass1ThatNeedsSharedClassObj {
    //it should get the required object
}

export class ProjectClass2ThatNeedsSharedClassObj {
    //it should get the required object
}

How can I write a simple DI to achieve this functionality?

Answer 1

If you want enforce a single object through all methods of DI, you can use a static variable. This is the pattern I normally use

export class SearchProvider {
  private static _default: SearchProvider

  constructor() {
  }

  static get Default() {
    return this._default || (this._default = new SearchProvider())
  }
}

export class Consumer() {
  private SearchProvider _provider = SearchProvider.Default;
}

Answer 2

1)Create that class as a service with @Injectable decorator 2)Import that class into class where you want to use it 3)create a instance of service class into that class 4)now you can access methods of service class using instance created in constructor using this keyword & . operator 5)You have to write service class once & use it many times as you want

Happy coding