javascript 保存自https://classroom.udacity.com/nanodegrees/nd001/parts/4942f4d7-a48d-4794-9eb0-404b3ed3

Posted 2021-05-03

class Tree {
  constructor(size = '10', leaves = {spring: 'green', summer: 'green', fall: 'orange', winter: null}) {
    this.size = size;
    this.leaves = leaves;
    this.leafColor = null;
  }

  changeSeason(season) {
    this.leafColor = this.leaves[season];
    if (season === 'spring') {
      this.size += 1;
    }
  }
}

class Maple extends Tree {
  constructor(syrupQty = 15, size, leaves) {
    super(size, leaves);
    this.syrupQty = syrupQty;
  }

  changeSeason(season) {
    super.changeSeason(season);
    if (season === 'spring') {
      this.syrupQty += 1;
    }
  }

  gatherSyrup() {
    this.syrupQty -= 3;
  }
}

const myMaple = new Maple(15, 5);
myMaple.changeSeason('fall');
myMaple.gatherSyrup();
myMaple.changeSeason('spring');