Class to represent a Complex number and a few operations that can be done with them

complex.js

class Complex {
    constructor(real, imag) {
        this.real = real
        this.imag = imag
    }

    length() {
        return Math.sqrt(this.real * this.real + this.imag * this.imag)
    }

    mul(other) {
        // first outers inners lasts
        // (aR+aI)(bR+bI) = aR * bR + 
        //                  aR * bI + 
        //                  aI * bR + 
        //                  aI * bI => -a*b
        //               
        return new Complex(this.real * other.real - this.imag * other.imag, 
                           this.real * other.imag + this.imag * other.real)
    }

    add(other) {
        return new Complex(this.real + other.real, this.imag + other.imag)
    }

    square() {
        return this.mul(this)
    }

}