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TypeScript - interface getter

14 points
Created by:
Marcin
2447

In TypeScript does not allow to add getters directly to interface. It is possible to specyfy only property in interface that can be implemeneted as getter in following way.

Interface getter example

interface Square {
    readonly name: string;

    readonly x: number;
    readonly y: number;
}

class LocalSquare implements Square {

    public constructor(private _name: string, 
        private _x: number = 0, private _y: number = 0) {
        // nothing here...
    }

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

    get x(): number {
        return this._x;
    }

    get y(): number {
        return this._y;
    }
}

let a = new LocalSquare('A', 1, 2);

console.log(`${a.name}(${a.x}, ${a.y})`);

Complilation and running:

$ tsc --target ES5 Script.ts
$ node Script.js

Output:

A(1, 2)

Run it online here. 

Notes:

  • to enable getters support --targer ES5 parameter during complilation is necessary (check full list of targets here)
  • readonly keyword in interface is optional

References

  1. Readonly properties - Microsoft Docs
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