freeCodeCamp/curriculum/challenges/chinese/02-javascript-algorithms-an.../basic-javascript/accessing-nested-objects.md

1.8 KiB

id title challengeType videoUrl forumTopicId dashedName
56533eb9ac21ba0edf2244cc 访问嵌套对象 1 https://scrimba.com/c/cRnRnfa 16161 accessing-nested-objects

--description--

我们可以通过连续使用点号表示法和方括号表示法来访问对象的嵌套属性。

这是一个嵌套对象:

var ourStorage = {
  "desk": {
    "drawer": "stapler"
  },
  "cabinet": {
    "top drawer": { 
      "folder1": "a file",
      "folder2": "secrets"
    },
    "bottom drawer": "soda"
  }
};
ourStorage.cabinet["top drawer"].folder2;
ourStorage.desk.drawer;

ourStorage.cabinet["top drawer"].folder2 将会是字符串 secrets,并且 ourStorage.desk.drawer 将会是字符串 stapler

--instructions--

访问 myStorage 对象并将 glove box 属性的内容赋值给 gloveBoxContents 变量。 在可能的情况下,对所有的属性使用点号,否则使用方括号。

--hints--

gloveBoxContents 应该等于字符串 maps

assert(gloveBoxContents === 'maps');

你的代码应该使用点号和方括号来访问 myStorage

assert(/=\s*myStorage\.car\.inside\[\s*("|')glove box\1\s*\]/g.test(code));

--seed--

--after-user-code--

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

--seed-contents--

var myStorage = {
  "car": {
    "inside": {
      "glove box": "maps",
      "passenger seat": "crumbs"
     },
    "outside": {
      "trunk": "jack"
    }
  }
};

var gloveBoxContents = undefined;

--solutions--

var myStorage = {
  "car":{
    "inside":{
      "glove box":"maps",
      "passenger seat":"crumbs"
    },
    "outside":{
      "trunk":"jack"
    }
  }
};
var gloveBoxContents = myStorage.car.inside["glove box"];