Inheritance Without class

Explain how inheritance works in JavaScript, then write this pair using functions only:

class Polygon {
  constructor(height, width) {
    this.height = height;
    this.width = width;
  }
  area() {
    return this.height * this.width;
  }
}

class Square extends Polygon {
  constructor(side) {
    super(side, side);
  }
  setSide(n) {
    this.height = this.width = n;
  }
}

Rules

• Polygon and Square are constructor functions. The grader reads their source, so class syntax fails.
• Fields live on instances, and methods live on prototypes, shared by every instance.
• Square.prototype inherits from Polygon.prototype, instanceof works for both, and each prototype's constructor points back to its function.
• Square.prototype carries no height or width of its own.