2018-10-10 22:03:03 +00:00
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---
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id: 56bbb991ad1ed5201cd392d0
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2021-03-15 03:20:39 +00:00
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title: 创建 JavaScript 对象
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2018-10-10 22:03:03 +00:00
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challengeType: 1
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2020-04-29 10:29:13 +00:00
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videoUrl: 'https://scrimba.com/c/cWGkbtd'
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forumTopicId: 16769
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2021-01-13 02:31:00 +00:00
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dashedName: build-javascript-objects
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2018-10-10 22:03:03 +00:00
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---
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2020-12-16 07:37:30 +00:00
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# --description--
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2021-03-15 03:20:39 +00:00
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你之前可能听过 `object` 这个词。
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2020-12-16 07:37:30 +00:00
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2021-03-15 03:20:39 +00:00
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对象和 `arrays` 类似,区别在于数组使用索引来访问和修改数据,而对象中的数据是通过 `properties` 访问的。
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2020-12-16 07:37:30 +00:00
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2021-03-15 03:20:39 +00:00
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对象非常适合用来存储结构化数据,可以表示真实世界中的物体,比如一只猫。
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2020-12-16 07:37:30 +00:00
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2021-03-15 03:20:39 +00:00
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这里是一个猫对象的样本:
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2020-04-29 10:29:13 +00:00
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```js
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var cat = {
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"name": "Whiskers",
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"legs": 4,
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"tails": 1,
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"enemies": ["Water", "Dogs"]
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};
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```
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2021-03-15 03:20:39 +00:00
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在这个示例中,所有的属性都被纯属为字符串,比如 `name`、`legs` 和 `tails`。 然而,你也可以使用数字作为属性。 你甚至可以省略单字字符串属性中的引号,如下所示:
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2020-04-29 10:29:13 +00:00
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```js
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var anotherObject = {
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make: "Ford",
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5: "five",
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"model": "focus"
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};
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```
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2021-03-15 03:20:39 +00:00
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然而,如果你的对象有非字符串属性的话,JavaScript 会自动将它们转为字符串。
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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# --instructions--
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2018-10-10 22:03:03 +00:00
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2021-03-15 03:20:39 +00:00
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确保对象表示一只名为 `myDog` 的狗,包含属性 `name`(字符串)、`legs`、`tails` 和 `friends`。
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2018-10-10 22:03:03 +00:00
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2021-03-15 03:20:39 +00:00
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你可以随意设置这些对象的属性值,只要 `name` 是字符串,`legs` 和 `tails` 是数字,`friends` 是数组即可。
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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# --hints--
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2018-10-10 22:03:03 +00:00
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2021-03-15 03:20:39 +00:00
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`myDog` 应该包含 `name` 属性,并且它应该是一个 `string`。
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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```js
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assert(
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(function (z) {
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if (
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z.hasOwnProperty('name') &&
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z.name !== undefined &&
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typeof z.name === 'string'
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) {
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return true;
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} else {
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return false;
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}
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})(myDog)
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);
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2018-10-10 22:03:03 +00:00
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```
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2021-03-15 03:20:39 +00:00
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`myDog`应该包含 `legs` 属性,并且它应该是一个 `number`。
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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```js
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assert(
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(function (z) {
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if (
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z.hasOwnProperty('legs') &&
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z.legs !== undefined &&
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typeof z.legs === 'number'
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) {
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return true;
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} else {
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return false;
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}
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})(myDog)
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);
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```
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2018-10-10 22:03:03 +00:00
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2021-03-15 03:20:39 +00:00
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`myDog` 应该包含 `tails` 属性,并且它应该是一个 `number`。
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2018-10-10 22:03:03 +00:00
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```js
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2020-12-16 07:37:30 +00:00
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assert(
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(function (z) {
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if (
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z.hasOwnProperty('tails') &&
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z.tails !== undefined &&
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typeof z.tails === 'number'
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) {
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return true;
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} else {
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return false;
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}
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})(myDog)
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);
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2018-10-10 22:03:03 +00:00
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```
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2021-03-15 03:20:39 +00:00
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`myDog` 应该包含 `friends` 属性,并且它应该是一个 `array`。
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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```js
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assert(
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(function (z) {
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if (
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z.hasOwnProperty('friends') &&
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z.friends !== undefined &&
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Array.isArray(z.friends)
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) {
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return true;
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} else {
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return false;
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}
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})(myDog)
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);
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```
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2018-10-10 22:03:03 +00:00
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2021-03-15 03:20:39 +00:00
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`myDog` 只应该包含所有给定的属性。
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2020-04-29 10:29:13 +00:00
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2018-10-10 22:03:03 +00:00
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```js
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2020-12-16 07:37:30 +00:00
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assert(
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(function (z) {
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return Object.keys(z).length === 4;
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})(myDog)
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);
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2018-10-10 22:03:03 +00:00
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```
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2020-04-29 10:29:13 +00:00
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2021-01-13 02:31:00 +00:00
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# --seed--
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## --after-user-code--
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```js
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(function(z){return z;})(myDog);
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```
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## --seed-contents--
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```js
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var myDog = {
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// Only change code below this line
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// Only change code above this line
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};
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```
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2020-12-16 07:37:30 +00:00
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# --solutions--
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2021-01-13 02:31:00 +00:00
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```js
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var myDog = {
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"name": "Camper",
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"legs": 4,
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"tails": 1,
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"friends": ["everything!"]
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};
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```
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