Hari 11: Class dengan TypeScript

Class di TypeScript

class Produk {
    readonly id: number;
    private _stok: number;

    constructor(
        id: number,
        public nama: string,     // shorthand property declaration
        public harga: number,
        stok: number = 0,
    ) {
        this.id    = id;
        this._stok = stok;
    }

    get stok(): number { return this._stok; }

    set stok(nilai: number) {
        if (nilai < 0) throw new RangeError("Stok tidak boleh negatif");
        this._stok = nilai;
    }

    tampilkan(): string {
        return `[${this.id}] ${this.nama} - Rp ${this.harga.toLocaleString()} (stok: ${this._stok})`;
    }
}

const laptop = new Produk(1, "Laptop", 8500000, 10);
laptop.stok = 15;
console.log(laptop.tampilkan());

Abstract Class

abstract class Bentuk {
    abstract luas(): number;
    abstract keliling(): number;

    deskripsi(): string {
        return `Luas: ${this.luas().toFixed(2)}, Keliling: ${this.keliling().toFixed(2)}`;
    }
}

class Lingkaran extends Bentuk {
    constructor(private r: number) { super(); }
    luas(): number     { return Math.PI * this.r ** 2; }
    keliling(): number { return 2 * Math.PI * this.r; }
}

const c = new Lingkaran(7);
console.log(c.deskripsi()); // Luas: 153.94, Keliling: 43.98