CODEWITHSUNDEEP
typescript
David Mason
David Mason

Reputation: 329

"new() =>" in typescript constructor

I just found a code snipped in TypeScript what I do not really understand. 

export abstract class Presenter<TView> {
  public viewModel: TView;

  constructor(private template: new() => TView,
  ) {
  }

  public reset(): void {
    const model = new this.template();

    if (this.viewModel == null) {
      this.viewModel = model;
    } else {
      Object.assign(this.viewModel, model);
    }
  }
}

I am especially talking about the template: new() => TView here. I can see that it is a generic class and if a type parameter "string" was used, the code in the constructor would resolve to:

new() => string

here.

But I cannot help myself understanding the sense of that. Its not a function declaration - I never saw "new" in such a context. Also I do not know what:

const model = new this.template();

means than. Can anybody explain?

Upvotes: 1

Views: 745

Answers (1)

Jonas H&#248;gh
Jonas H&#248;gh

Reputation: 10874

This means that template is a constructor with no parameters, that returns a TView when invoked with new. It is described here in the typescript handbook.

Upvotes: 1

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