javascript - “for”循环未正确循环对象数组

Question

当我运行以下非常简单的代码时，由于某种原因，我在浏览器控制台中得到以下结果:“6 You have not saw undefined undefined.”谁能指出我的错误吗？

var movies = [{
    title: "The Mummy",
    hasWatched: true,
    stars: "5 stars"
  },

  {
    title: "About A Boy",
    hasWatched: true,
    stars: "5 stars"
  },


  {
    title: "It",
    hasWatched: false,
    stars: "5 stars"
  },


  {
    title: "Cleopatra",
    hasWatched: false,
    stars: "5 stars"
  }

];

for (var i = 0; i <= movies.length; i++) {
  if (movies.hasWatched) {
    console.log("You have watched " + movies.title + " " + movies.stars + ".");
  } else {
    console.log("You have not watched " + movies.title + " " + movies.stars + ".");
  }

}

Answer 1

您有一个对象数组，因此需要引用每个数组元素的索引。您还需要将循环减少一，因为数组索引是从零开始的，但长度不是。

var movies = [{
    title: "The Mummy",
    hasWatched: true,
    stars: "5 stars"
  },

  {
    title: "About A Boy",
    hasWatched: true,
    stars: "5 stars"
  },


  {
    title: "It",
    hasWatched: false,
    stars: "5 stars"
  },


  {
    title: "Cleopatra",
    hasWatched: false,
    stars: "5 stars"
  }

];

for (var i = 0; i < movies.length; i++) {
  if (movies[i].hasWatched) {
    console.log("You have watched " + movies[i].title + " " + movies[i].stars + ".");
  } else {
    console.log("You have not watched " + movies[i].title + " " + movies[i].stars + ".");
  }

}