exercises of js-and-dom-for-gecko-hackers-talk

exercises-1.js

/*
Source: https://github.com/mikeconley/js-and-dom-for-gecko-hackers-talk
site: https://askeing.github.io/js-and-dom-for-gecko-hackers-talk/
slide-64
*/

function Shape({ x, y }) {
  this._x = x;
  this._y = y;
}

Shape.prototype = {
  get coords() {
    return { x: this._x, y: this._y };
  },
}

// Implement Rect, which subclasses Shape. In addition to
// the x and y coordinate parameters, should also take height
// and width. Should also have a isSquare getter that returns
// true if the Rect is square.
function Rect({x, y, h, w}) {
    Shape.call(this, {x, y});
    this._h = h;
    this._w = w;
    this.isSquare = (this._h == this._w);
}

Rect.prototype = Object.create(Shape.prototype);
/*
// it can only be used by `s.isSquare()`
Rect.prototype.isSquare = function() {
    if (this._h == this._w) {
        return true;
    }
    return false;
}*/

let s = new Rect({ x: 5, y: 5, h: 25, w: 25 });
console.log(s.isSquare);

let rects = [
  new Rect({ x: 0, y: 0, h: 5, w: 100 }),
  new Rect({ x: 0, y: 5, h: 13, w: 2 }),
  new Rect({ x: 10, y: 10, h: 15, w: 15 }),
  new Rect({ x: 16, y: -5, h: 3, w: 3 }),
];

// Iterate the rects using for...of, and console.log
// isSquare for each.
for (let r of rects) {
    console.log(r.isSquare);
}

/*
// Using object destructuring to assign the coords of
// s to local variables x and y in a single line.
*/
let {_x: x, _y: y} = new Rect({ x: 16, y: -5, h: 3, w: 3 });
console.log(x, y)