ee1e8abd87
* feat(tools): add seed/solution restore script * chore(curriculum): remove empty sections' markers * chore(curriculum): add seed + solution to Chinese * chore: remove old formatter * fix: update getChallenges parse translated challenges separately, without reference to the source * chore(curriculum): add dashedName to English * chore(curriculum): add dashedName to Chinese * refactor: remove unused challenge property 'name' * fix: relax dashedName requirement * fix: stray tag Remove stray `pre` tag from challenge file. Signed-off-by: nhcarrigan <nhcarrigan@gmail.com> Co-authored-by: nhcarrigan <nhcarrigan@gmail.com>
115 lines
2.1 KiB
Markdown
115 lines
2.1 KiB
Markdown
---
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id: 56533eb9ac21ba0edf2244dd
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title: 使用 Switch 语句从许多选项中进行选择
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challengeType: 1
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videoUrl: 'https://scrimba.com/c/c4mv4fm'
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forumTopicId: 18277
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dashedName: selecting-from-many-options-with-switch-statements
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---
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# --description--
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如果你有非常多的选项需要选择，可以使用 switch 语句。根据不同的参数值会匹配上不同的 case 分支，语句会从第一个匹配的 case 分支开始执行，直到碰到 break 就结束。
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这是一个伪代码案例：
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```js
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switch(lowercaseLetter) {
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case "a":
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console.log("A");
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break;
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case "b":
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console.log("B");
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break;
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}
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```
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测试`case`值使用严格相等运算符进行比较，break 关键字告诉 JavaScript 停止执行语句。如果没有 break 关键字，下一个语句会继续执行。
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# --instructions--
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写一个测试`val`的 switch 语句，并且根据下面的条件来设置不同的`answer`：
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`1`- "alpha"
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`2` - "beta"
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`3`- "gamma"
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`4` - "delta"
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# --hints--
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`caseInSwitch(1)` 应该有一个值为 "alpha"。
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```js
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assert(caseInSwitch(1) === 'alpha');
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```
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`caseInSwitch(2)` 应该有一个值为 "beta"。
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```js
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assert(caseInSwitch(2) === 'beta');
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```
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`caseInSwitch(3)` 应该有一个值为 "gamma"。
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```js
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assert(caseInSwitch(3) === 'gamma');
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```
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`caseInSwitch(4)` 应该有一个值为 "delta"。
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```js
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assert(caseInSwitch(4) === 'delta');
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```
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不能使用任何`if`或`else`表达式。
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```js
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assert(!/else/g.test(code) || !/if/g.test(code));
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```
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你应该有至少 3 个`break`表达式。
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```js
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assert(code.match(/break/g).length > 2);
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```
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# --seed--
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## --seed-contents--
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```js
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function caseInSwitch(val) {
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var answer = "";
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// Only change code below this line
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// Only change code above this line
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return answer;
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}
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caseInSwitch(1);
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```
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# --solutions--
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```js
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function caseInSwitch(val) {
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var answer = "";
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switch(val) {
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case 1:
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answer = "alpha";
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break;
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case 2:
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answer = "beta";
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break;
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case 3:
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answer = "gamma";
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break;
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case 4:
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answer = "delta";
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}
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return answer;
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}
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```
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