89 lines
3.5 KiB
Markdown
89 lines
3.5 KiB
Markdown
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---
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id: 56533eb9ac21ba0edf2244e0
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title: Replacing If Else Chains with Switch
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challengeType: 1
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videoUrl: ''
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localeTitle: 如果用交换机替换其他链条
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---
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## Description
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<section id="description">如果您有许多选项可供选择，那么<code>switch</code>语句比许多链接的<code>if</code> / <code>else if</code>语句更容易编写。下列： <blockquote> if（val === 1）{ <br> answer =“a”; <br> } else if（val === 2）{ <br> answer =“b”; <br> } else { <br> answer =“c”; <br> } </blockquote>可以替换为： <blockquote> switch（val）{ <br>情况1： <br> answer =“a”; <br>打破; <br>案例2： <br> answer =“b”; <br>打破; <br>默认： <br> answer =“c”; <br> } </blockquote></section>
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## Instructions
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<section id="instructions">将链接的<code>if</code> / <code>else if</code>语句更改为<code>switch</code>语句。 </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: 您不应该在编辑器中的任何位置使用任何<code>else</code>语句
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testString: 'assert(!/else/g.test(code), "You should not use any <code>else</code> statements anywhere in the editor");'
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- text: 您不应在编辑器中的任何位置使用任何<code>if</code>语句
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testString: 'assert(!/if/g.test(code), "You should not use any <code>if</code> statements anywhere in the editor");'
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- text: 你应该至少有四个<code>break</code>语句
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testString: 'assert(code.match(/break/g).length >= 4, "You should have at least four <code>break</code> statements");'
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- text: <code>chainToSwitch("bob")</code>应该是“Marley”
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testString: 'assert(chainToSwitch("bob") === "Marley", "<code>chainToSwitch("bob")</code> should be "Marley"");'
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- text: <code>chainToSwitch(42)</code>应该是“答案”
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testString: 'assert(chainToSwitch(42) === "The Answer", "<code>chainToSwitch(42)</code> should be "The Answer"");'
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- text: <code>chainToSwitch(1)</code>应该是“没有＃1”
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testString: 'assert(chainToSwitch(1) === "There is no #1", "<code>chainToSwitch(1)</code> should be "There is no #1"");'
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- text: <code>chainToSwitch(99)</code>应该是“错过了我这么多！”
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testString: 'assert(chainToSwitch(99) === "Missed me by this much!", "<code>chainToSwitch(99)</code> should be "Missed me by this much!"");'
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- text: <code>chainToSwitch(7)</code>应该是“Ate Nine”
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testString: 'assert(chainToSwitch(7) === "Ate Nine", "<code>chainToSwitch(7)</code> should be "Ate Nine"");'
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- text: <code>chainToSwitch("John")</code>应为“”（空字符串）
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testString: 'assert(chainToSwitch("John") === "", "<code>chainToSwitch("John")</code> should be "" (empty string)");'
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- text: <code>chainToSwitch(156)</code>应为“”（空字符串）
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testString: 'assert(chainToSwitch(156) === "", "<code>chainToSwitch(156)</code> should be "" (empty string)");'
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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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function chainToSwitch(val) {
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var answer = "";
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// Only change code below this line
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if (val === "bob") {
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answer = "Marley";
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} else if (val === 42) {
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answer = "The Answer";
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} else if (val === 1) {
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answer = "There is no #1";
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} else if (val === 99) {
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answer = "Missed me by this much!";
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} else if (val === 7) {
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answer = "Ate Nine";
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}
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// Only change code above this line
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return answer;
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}
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// Change this value to test
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chainToSwitch(7);
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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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