freeCodeCamp/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-nested-arrays.md

id, title, challengeType, videoUrl, forumTopicId, dashedName

id	title	challengeType	videoUrl	forumTopicId	dashedName
56533eb9ac21ba0edf2244cd	访问嵌套数组	1	https://scrimba.com/c/cLeGDtZ	16160	accessing-nested-arrays

--description--

正如我们在前面的例子所见，对象可以嵌套对象和数组。与访问嵌套对象一样，用中括号操作符同样可以访问嵌套数组。

下面是如何访问嵌套数组的例子：

var ourPets = [
  {
    animalType: "cat",
    names: [
      "Meowzer",
      "Fluffy",
      "Kit-Cat"
    ]
  },
  {
    animalType: "dog",
    names: [
      "Spot",
      "Bowser",
      "Frankie"
    ]
  }
];
ourPets[0].names[1]; // "Fluffy"
ourPets[1].names[0]; // "Spot"

--instructions--

使用点操作符和中括号操作符来检索变量myPlants的第二棵树。

--hints--

secondTree应该等于 "pine"。

assert(secondTree === 'pine');

使用点操作符和中括号操作符来检索变量myPlants。

assert(/=\s*myPlants\[1\].list\[1\]/.test(code));

--seed--

--after-user-code--

(function(x) {
  if(typeof x != 'undefined') {
    return "secondTree = " + x;
  }
  return "secondTree is undefined";
})(secondTree);

--seed-contents--

// Setup
var myPlants = [
  {
    type: "flowers",
    list: [
      "rose",
      "tulip",
      "dandelion"
    ]
  },
  {
    type: "trees",
    list: [
      "fir",
      "pine",
      "birch"
    ]
  }
];

// Only change code below this line

var secondTree = ""; // Change this line

--solutions--

var myPlants = [
  {
    type: "flowers",
    list: [
      "rose",
      "tulip",
      "dandelion"
    ]
  },
  {
    type: "trees",
    list: [
      "fir",
      "pine",
      "birch"
    ]
  }
];

// Only change code below this line

var secondTree = myPlants[1].list[1];