124 lines
1.9 KiB
Markdown
124 lines
1.9 KiB
Markdown
---
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id: 56533eb9ac21ba0edf2244cd
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title: 访问嵌套数组
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challengeType: 1
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videoUrl: 'https://scrimba.com/c/cLeGDtZ'
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forumTopicId: 16160
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dashedName: accessing-nested-arrays
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---
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# --description--
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在之前的挑战中，我们学习了在对象中嵌套对象和数组。与访问嵌套的对象一样，我们可以用方括号表示法来访问嵌套数组。
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下面是访问嵌套数组的例子：
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```js
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var ourPets = [
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{
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animalType: "cat",
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names: [
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"Meowzer",
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"Fluffy",
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"Kit-Cat"
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]
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},
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{
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animalType: "dog",
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names: [
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"Spot",
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"Bowser",
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"Frankie"
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]
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}
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];
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ourPets[0].names[1]; // "Fluffy"
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ourPets[1].names[0]; // "Spot"
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```
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# --instructions--
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请使用点号表示法和方括号表示法来检索变量 `myPlants` 中的第二棵树，即返回 `type` 为 `trees` 的数组中的第二个元素。
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# --hints--
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`secondTree` 的值应为 "pine"。
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```js
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assert(secondTree === 'pine');
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```
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应使用点号表示法和方括号表示法来检索变量 `myPlants`。
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```js
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assert(/=\s*myPlants\[1\].list\[1\]/.test(code));
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```
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# --seed--
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## --after-user-code--
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```js
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(function(x) {
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if(typeof x != 'undefined') {
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return "secondTree = " + x;
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}
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return "secondTree is undefined";
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})(secondTree);
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```
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## --seed-contents--
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```js
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// Setup
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var myPlants = [
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{
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type: "flowers",
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list: [
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"rose",
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"tulip",
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"dandelion"
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]
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},
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{
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type: "trees",
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list: [
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"fir",
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"pine",
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"birch"
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]
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}
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];
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// Only change code below this line
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var secondTree = ""; // Change this line
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```
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# --solutions--
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```js
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var myPlants = [
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{
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type: "flowers",
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list: [
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"rose",
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"tulip",
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"dandelion"
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]
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},
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{
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type: "trees",
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list: [
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"fir",
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"pine",
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"birch"
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]
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}
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];
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// Only change code below this line
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var secondTree = myPlants[1].list[1];
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```
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