104 lines
2.3 KiB
Markdown
104 lines
2.3 KiB
Markdown
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---
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id: 56533eb9ac21ba0edf2244c8
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title: 使用方括號表示法訪問對象屬性
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challengeType: 1
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videoUrl: 'https://scrimba.com/c/cBvmEHP'
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forumTopicId: 16163
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dashedName: accessing-object-properties-with-bracket-notation
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---
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# --description--
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訪問對象屬性的第二種方式是方括號表示法(`[]`)。 如果你想訪問的屬性名中包含空格,就必須使用方括號表示法來獲取它的屬性值。
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當然,如果屬性名不包含空格,也可以使用方括號表示法。
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這是一個使用方括號表示法讀取對象屬性的例子:
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```js
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var myObj = {
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"Space Name": "Kirk",
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"More Space": "Spock",
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"NoSpace": "USS Enterprise"
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};
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myObj["Space Name"];
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myObj['More Space'];
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myObj["NoSpace"];
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```
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`myObj["Space Name"]` 將會是字符串 `Kirk`,`myObj['More Space']` 將會是字符串 `Spock`,並且`myObj["NoSpace"]` 將會是字符串 `USS Enterprise`。
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注意,如果屬性名中包含空格,就必須使用引號(單引號或雙引號)將它們包裹起來。
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# --instructions--
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使用方括號讀取 `testObj` 中 `an entree` 和 `the drink` 的屬性值,並分別將它們賦值給 `entreeValue` 和 `drinkValue`。
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# --hints--
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`entreeValue` 應該是一個字符串。
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```js
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assert(typeof entreeValue === 'string');
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```
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`entreeValue` 的值應該爲字符串 `hamburger`
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```js
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assert(entreeValue === 'hamburger');
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```
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`drinkValue` 應該是一個字符串
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```js
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assert(typeof drinkValue === 'string');
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```
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`drinkValue` 的值應該爲字符串 `water`
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```js
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assert(drinkValue === 'water');
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```
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你應該使用兩次方括號
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```js
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assert(code.match(/testObj\s*?\[('|")[^'"]+\1\]/g).length > 1);
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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(a,b) { return "entreeValue = '" + a + "', drinkValue = '" + b + "'"; })(entreeValue,drinkValue);
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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 testObj = {
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"an entree": "hamburger",
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"my side": "veggies",
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"the drink": "water"
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};
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// Only change code below this line
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var entreeValue = testObj; // Change this line
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var drinkValue = testObj; // Change this line
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```
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# --solutions--
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```js
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var testObj = {
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"an entree": "hamburger",
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"my side": "veggies",
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"the drink": "water"
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};
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var entreeValue = testObj["an entree"];
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var drinkValue = testObj['the drink'];
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```
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