101 lines
2.4 KiB
Markdown
101 lines
2.4 KiB
Markdown
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---
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id: a0b5010f579e69b815e7c5d6
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title: 搜索與替換
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challengeType: 5
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forumTopicId: 16045
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dashedName: search-and-replace
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---
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# --description--
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在這道題目中，我們需要寫一個字符串的搜索與替換函數，它的返回值爲完成替換後的新字符串。
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這個函數接收的第一個參數爲待替換的句子。
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第二個參數爲句中需要被替換的單詞。
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第三個參數爲替換後的單詞。
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**注意：** 在更換原始單詞時保留原始單詞中第一個字符的大小寫。 即如果傳入的第二個參數爲 `Book`，第三個參數爲 `dog`，那麼替換後的結果應爲 `Dog`
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# --hints--
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`myReplace("Let us go to the store", "store", "mall")` 應返回 `Let us go to the mall`。
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```js
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assert.deepEqual(
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myReplace('Let us go to the store', 'store', 'mall'),
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'Let us go to the mall'
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);
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```
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`myReplace("He is Sleeping on the couch", "Sleeping", "sitting")` 應返回 `He is Sitting on the couch`。
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```js
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assert.deepEqual(
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myReplace('He is Sleeping on the couch', 'Sleeping', 'sitting'),
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'He is Sitting on the couch'
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);
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```
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`myReplace("I think we should look up there", "up", "Down")` 應返回 `I think we should look down there`。
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```js
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assert.deepEqual(
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myReplace('I think we should look up there', 'up', 'Down'),
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'I think we should look down there'
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);
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```
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`myReplace("This has a spellngi error", "spellngi", "spelling")` 應返回 `This has a spelling error`。
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```js
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assert.deepEqual(
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myReplace('This has a spellngi error', 'spellngi', 'spelling'),
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'This has a spelling error'
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);
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```
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`myReplace("His name is Tom", "Tom", "john")` 應返回 `His name is John`。
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```js
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assert.deepEqual(
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myReplace('His name is Tom', 'Tom', 'john'),
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'His name is John'
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);
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```
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`myReplace("Let us get back to more Coding", "Coding", "algorithms")` 應返回 `Let us get back to more Algorithms`。
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```js
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assert.deepEqual(
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myReplace('Let us get back to more Coding', 'Coding', 'algorithms'),
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'Let us get back to more Algorithms'
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);
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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 myReplace(str, before, after) {
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return str;
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}
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myReplace("A quick brown fox jumped over the lazy dog", "jumped", "leaped");
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```
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# --solutions--
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```js
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function myReplace(str, before, after) {
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if (before.charAt(0) === before.charAt(0).toUpperCase()) {
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after = after.charAt(0).toUpperCase() + after.substring(1);
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} else {
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after = after.charAt(0).toLowerCase() + after.substring(1);
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}
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return str.replace(before, after);
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}
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```
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