129 lines
2.1 KiB
Markdown
129 lines
2.1 KiB
Markdown
---
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id: 56533eb9ac21ba0edf2244de
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title: 在 switch 语句中添加默认选项
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challengeType: 1
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videoUrl: 'https://scrimba.com/c/c3JvVfg'
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forumTopicId: 16653
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dashedName: adding-a-default-option-in-switch-statements
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---
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# --description--
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在 `switch` 语句中，你可能无法用 `case` 枚举出所有可能的值。 相反，你可以添加 `default` 语句，它会在找不到相匹配的 `case` 语句之后执行。 你可以把它看作是 `if/else` 链中最后的那个 `else` 语句。
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`default` 语句应该被放到最后。
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```js
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switch (num) {
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case value1:
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statement1;
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break;
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case value2:
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statement2;
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break;
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...
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default:
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defaultStatement;
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break;
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}
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```
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# --instructions--
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写一个 switch 语句，设置以下条件设置 `answer`：
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`a` - `apple`
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`b` - `bird`
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`c` - `cat`
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`default` - `stuff`
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# --hints--
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`switchOfStuff("a")` 应该返回字符串 `apple`
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```js
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assert(switchOfStuff('a') === 'apple');
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```
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`switchOfStuff("b")` 应该返回字符串 `bird`
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```js
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assert(switchOfStuff('b') === 'bird');
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```
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`switchOfStuff("c")` 应该返回字符串 `cat`
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```js
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assert(switchOfStuff('c') === 'cat');
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```
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`switchOfStuff("d")` 应该返回字符串 `stuff`
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```js
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assert(switchOfStuff('d') === 'stuff');
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```
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`switchOfStuff(4)` 应该返回字符串 `stuff`
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```js
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assert(switchOfStuff(4) === 'stuff');
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```
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不能使用 `if` 或 `else` 语句。
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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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你应该使用 `default` 语句。
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```js
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assert(switchOfStuff('string-to-trigger-default-case') === 'stuff');
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```
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你至少应该写 3 个 `break` 语句。
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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 switchOfStuff(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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switchOfStuff(1);
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```
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# --solutions--
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```js
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function switchOfStuff(val) {
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var answer = "";
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switch(val) {
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case "a":
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answer = "apple";
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break;
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case "b":
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answer = "bird";
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break;
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case "c":
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answer = "cat";
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break;
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default:
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answer = "stuff";
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}
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return answer;
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}
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```
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