SOURCE

class Complex {
    // 
    constructor(real, imaginary) {
        this.r = real;
        this.i = imaginary;
    }
    plus(that) {
        return new Complex(this.r + that.r, this.i + that.i);
    }
    times(that) {
        return new Complex(this.r * that.r - this.i * that.i,
            this.r * that.r + this.i * that.r);
    }
    static sum(c, d) {
        return c.plus(d);
    }
    static product(c, d) { return c.times(d); }

    get real() { return this.r }
    get imaginary() { return this.i; }
    get magnitude() { return Math.hypot(this.r, this.i); }

    toString() { return `${this.r},${this.i}` }
    equals(that) {
        return that instanceof Complex && this.r === that.r && this.i === that.i;
    }
}

Complex.ZERO = new Complex(0, 0);
Complex.ONE = new Complex(1, 0);
Complex.I = new Complex(0, 1);