CODEWITHSUNDEEP
typescript
MonkBen
MonkBen

Reputation: 644

Problem calling a public function that references a private function in typescript

I'm fairly new to typescript. In javascript, I would sometimes expose functions in a module through a single object (e.g. "services"). I'm trying to do the same thing in typescript but am having trouble. Here is my simplified code:

class Tester {
  public publicField = "public field";
  private privateField = "private field";

  public services() {
    return {
        service1: this.getThePrivateField
    };
  }

  public getThePublicField() {
    return this.publicField;
  }

  private getThePrivateField() {
    console.log("reached getThePrivateField");
    return this.privateField;
  }

}

const t = new Tester();
console.log(t.services().service1()); // returns undefined but WHY?

When I call t.services().service1(), I know the code gets inside the getThePrivateField function as I've put a console.log there. So why is the response undefined?

Upvotes: 0

Views: 208

Answers (1)

Vlad Vidac
Vlad Vidac

Reputation: 998

The problem is plain old javascript this confusion. To make what you're trying to achieve work you would need to call t.services().service1.bind(t)().

This arises from the fact that, in the function t.services().service1, this is actually the object you're returning from services(), which doesn't have any privateField key.

Upvotes: 1

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