freeCodeCamp/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-bracket-notation.chinese.md
2019-02-19 11:34:27 +03:00

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---
id: 56533eb9ac21ba0edf2244c8
title: Accessing Object Properties with Bracket Notation
challengeType: 1
videoUrl: ''
localeTitle: 使用括号表示法访问对象属性
---
## Description
<section id="description">访问对象属性的第二种方法是括号表示法( <code>[]</code> )。如果您尝试访问的对象的属性在其名称中有空格,则需要使用括号表示法。但是,您仍然可以在没有空格的对象属性上使用括号表示法。以下是使用括号表示法读取对象属性的示例: <blockquote> var myObj = { <br> “太空名称”:“柯克”, <br> “更多空间”“Spock” <br> “NoSpace”“USS Enterprise” <br> }; <br> myObj [“空间名称”]; //柯克<br> myObj [&#39;更多空间&#39;]; // Spock <br> MyObj中[ “无空间”]; // USS Enterprise </blockquote>请注意,其中包含空格的属性名称必须使用引号(单引号或双引号)。 </section>
## Instructions
<section id="instructions">使用括号表示法<code>testObj</code>属性<code>&quot;an entree&quot;</code> <code>testObj</code> <code>&quot;an entree&quot;</code><code>&quot;the drink&quot;</code><code>testObj</code> ,并分别将它们分配给<code>entreeValue</code><code>drinkValue</code></section>
## Tests
<section id='tests'>
```yml
tests:
- text: <code>entreeValue</code>应该是一个字符串
testString: 'assert(typeof entreeValue === "string" , "<code>entreeValue</code> should be a string");'
- text: <code>entreeValue</code>的值应该是<code>&quot;hamburger&quot;</code>
testString: 'assert(entreeValue === "hamburger" , "The value of <code>entreeValue</code> should be <code>"hamburger"</code>");'
- text: <code>drinkValue</code>应该是一个字符串
testString: 'assert(typeof drinkValue === "string" , "<code>drinkValue</code> should be a string");'
- text: <code>drinkValue</code>的值应该是<code>&quot;water&quot;</code>
testString: 'assert(drinkValue === "water" , "The value of <code>drinkValue</code> should be <code>"water"</code>");'
- text: 您应该使用括号表示法两次
testString: 'assert(code.match(/testObj\s*?\[("|")[^""]+\1\]/g).length > 1, "You should use bracket notation twice");'
```
</section>
## Challenge Seed
<section id='challengeSeed'>
<div id='js-seed'>
```js
// Setup
var testObj = {
"an entree": "hamburger",
"my side": "veggies",
"the drink": "water"
};
// Only change code below this line
var entreeValue = testObj; // Change this line
var drinkValue = testObj; // Change this line
```
</div>
### After Test
<div id='js-teardown'>
```js
console.info('after the test');
```
</div>
</section>
## Solution
<section id='solution'>
```js
// solution required
```
</section>