CODEWITHSUNDEEP
typescript
tranntus
tranntus

Reputation: 61

Compilation error with promise

When I compile this file I get the following error:

44:16 - error TS2693: 'Promise' only refers to a type, but is being used as a value here.

fighter.ts:44:14 - error TS2693: 'Promise' only refers to a type, but is being used as a value here.

44   return new Promise((resolve) => {

How can I describe the Promise correctly in this case?

export interface IFighter {
    _name: string;
    _health: number;
    _power: number;
    health: () => number;
    name: () => string;
    setDamage: (damage: number) => void;
    hit: (enemy: Fighter, point: number) => void;
    knockout: () => Promise<Promise<any>>;


}


export class Fighter implements IFighter { 
    _name: string;
    _health: number;
    _power: number;
  constructor(name: string, health: number, power: number) {
    this._name = name;
    this._health = health;
    this._power = power;
  }

  health(): number {
    return this._health;
  }

  name(): string {
    return this._name;
  }

  setDamage(damage: number): void {
    this._health = this._health - damage;
    console.log(`${this._name} got ${damage} dmg. ${this._health}hp less`);
  }

  hit(enemy: Fighter, point: number): void {
    let damage: number = point * this._power;
    enemy.setDamage(damage);
  }

  knockout(): Promise<any> {
    return new Promise((resolve) => {
      console.log("time is over");
      setTimeout(() => {
        resolve((): void => {});
      }, 500);
    });
  }
}

Upvotes: 0

Views: 152

Answers (2)

Titian Cernicova-Dragomir
Titian Cernicova-Dragomir

Reputation: 249476

The error you are specifically getting is probably due to the fact that you are targeting es5. es5 does not have promises built-in. There is a promise type, but not a promise constructor defined in the es5 typescript lib. If your runtime has the Promise constructor, or you have a polyfill for it, you can add a lib attribute to your tsconfig.json to tell typescript to add the definitions for promises (the full es2015 conforming promise).

{
    ....
    "lib": ["es5","es2015.promise","dom", "scripthost"] 
    ....
}

Edit As @Oleksii points out knockout: () => Promise<Promise<any>>; should be knockout: () => Promise<any> but that is not specially related to the error in the question.;

Upvotes: 2

Oleksii
Oleksii

Reputation: 1643

change you in your IFighter interface:

this one knockout: () => Promise<Promise<any>>;

to knockout: () => Promise<any>;

It makes no sense to write Promise<Promise<Promise<...<T>>>> because anyway it will be represented as Promise<T>

Upvotes: 2

Related Questions