78 lines
3.3 KiB
Markdown
78 lines
3.3 KiB
Markdown
---
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id: cf1111c1c12feddfaeb3bdef
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title: Use Conditional Logic with If Statements
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challengeType: 1
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videoUrl: ''
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localeTitle: 使用条件逻辑和If语句
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---
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## Description
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<section id="description"> <code>If</code>语句用于在代码中做出决定。关键字<code>if</code>告诉JavaScript在括号中定义的特定条件下执行花括号中的代码。这些条件称为<code>Boolean</code>条件，它们可能只是<code>true</code>或<code>false</code> 。当条件计算结果为<code>true</code> ，程序将执行花括号内的语句。当布尔条件的计算结果为<code>false</code> ，大括号内的语句将不会执行。 <strong>伪代码</strong> <blockquote> if（ <i>condition为true</i> ）{ <br> <i>声明被执行</i> <br> } </blockquote> <strong>例</strong> <blockquote>功能测试（myCondition）{ <br> if（myCondition）{ <br>回归“这是真的”; <br> } <br>返回“这是假的”; <br> } <br>测试（真）; //返回“这是真的” <br>测试（假）; //返回“这是假的” </blockquote>当使用值<code>true</code>调用<code>test</code> ， <code>if</code>语句将评估<code>myCondition</code>以查看它是否为<code>true</code> 。因为它是<code>true</code> ，函数返回<code>"It was true"</code> 。当我们使用<code>false</code>值调用<code>test</code>时， <code>myCondition</code> <em>不为</em> <code>true</code>并且不执行花括号中的语句，函数返回<code>"It was false"</code> 。 </section>
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## Instructions
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<section id="instructions">在函数内部创建一个<code>if</code>语句<code>"Yes, that was true"</code>如果参数<code>wasThatTrue</code>为<code>true</code>则返回<code>"Yes, that was true"</code> <code>"No, that was false"</code>否则返回<code>"No, that was false"</code> 。 </section>
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## Tests
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<section id='tests'>
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```yml
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tests:
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- text: <code>trueOrFalse</code>应该是一个函数
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testString: 'assert(typeof trueOrFalse === "function", "<code>trueOrFalse</code> should be a function");'
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- text: <code>trueOrFalse(true)</code>应该返回一个字符串
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testString: 'assert(typeof trueOrFalse(true) === "string", "<code>trueOrFalse(true)</code> should return a string");'
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- text: <code>trueOrFalse(false)</code>应该返回一个字符串
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testString: 'assert(typeof trueOrFalse(false) === "string", "<code>trueOrFalse(false)</code> should return a string");'
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- text: <code>trueOrFalse(true)</code>应该返回“是的，那是真的”
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testString: 'assert(trueOrFalse(true) === "Yes, that was true", "<code>trueOrFalse(true)</code> should return "Yes, that was true"");'
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- text: <code>trueOrFalse(false)</code>应该返回“No，that was false”
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testString: 'assert(trueOrFalse(false) === "No, that was false", "<code>trueOrFalse(false)</code> should return "No, that was false"");'
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```
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</section>
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## Challenge Seed
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<section id='challengeSeed'>
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<div id='js-seed'>
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```js
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// Example
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function ourTrueOrFalse(isItTrue) {
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if (isItTrue) {
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return "Yes, it's true";
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}
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return "No, it's false";
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}
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// Setup
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function trueOrFalse(wasThatTrue) {
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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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// Change this value to test
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trueOrFalse(true);
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```
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</div>
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</section>
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## Solution
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<section id='solution'>
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```js
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// solution required
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```
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</section>
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