97 lines
2.2 KiB
Markdown
97 lines
2.2 KiB
Markdown
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---
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id: 587d7b7e367417b2b2512b21
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title: 使用多個三元運算符
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challengeType: 1
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videoUrl: 'https://scrimba.com/c/cyWJBT4'
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forumTopicId: 301179
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dashedName: use-multiple-conditional-ternary-operators
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---
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# --description--
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在之前的挑戰中，你使用了一個條件運算符。 你也可以將多個運算符串聯在一起以檢查多種條件。
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下面的函數使用 `if`，`else if` 和 `else` 語句來檢查多個條件：
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```js
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function findGreaterOrEqual(a, b) {
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if (a === b) {
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return "a and b are equal";
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}
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else if (a > b) {
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return "a is greater";
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}
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else {
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return "b is greater";
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}
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}
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```
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以上函數可以使用多個三元運算符重寫：
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```js
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function findGreaterOrEqual(a, b) {
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return (a === b) ? "a and b are equal"
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: (a > b) ? "a is greater"
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: "b is greater";
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}
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```
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如上文所示，對多個三元運算符進行每個條件都是單獨一行的格式化被認爲是最佳做法。 使用多個三元運算符而沒有適當的縮進可能會使您的代碼難以理解。 例如：
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```js
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function findGreaterOrEqual(a, b) {
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return (a === b) ? "a and b are equal" : (a > b) ? "a is greater" : "b is greater";
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}
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```
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# --instructions--
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在 `checkSign` 函數中使用多個三元運算符來檢查數字是正數 ("positive")、負數 ("negative") 或零 ("zero")，使用 `findGreaterOrEqual` 裏面的建議縮進格式。 函數應返回 `positive`、`negative` 或 `zero`。
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# --hints--
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`checkSign` 應該使用多個三元運算符。
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```js
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assert(/.+?\s*?\?\s*?.+?\s*?:\s*?.+?\s*?\?\s*?.+?\s*?:\s*?.+?/gi.test(code));
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```
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`checkSign(10)` 應該返回字符串 `positive`。 注意區分大寫字母和小寫字母。
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```js
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assert(checkSign(10) === 'positive');
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```
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`checkSign(-12)` 應該返回字符串 `negative`。 注意區分大寫字母和小寫字母。
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```js
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assert(checkSign(-12) === 'negative');
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```
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`checkSign(0)` 應該返回字符串 `zero`. 注意區分大寫字母和小寫字母。
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```js
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assert(checkSign(0) === 'zero');
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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 checkSign(num) {
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}
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checkSign(10);
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```
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# --solutions--
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```js
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function checkSign(num) {
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return (num > 0) ? 'positive' : (num < 0) ? 'negative' : 'zero';
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}
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```
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