76 lines
1.7 KiB
Markdown
76 lines
1.7 KiB
Markdown
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---
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id: 587d7dba367417b2b2512ba8
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title: Check for All or None
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challengeType: 1
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forumTopicId: 301338
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dashedName: check-for-all-or-none
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---
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# --description--
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Sometimes the patterns you want to search for may have parts of it that may or may not exist. However, it may be important to check for them nonetheless.
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You can specify the possible existence of an element with a question mark, `?`. This checks for zero or one of the preceding element. You can think of this symbol as saying the previous element is optional.
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For example, there are slight differences in American and British English and you can use the question mark to match both spellings.
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```js
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let american = "color";
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let british = "colour";
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let rainbowRegex= /colou?r/;
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rainbowRegex.test(american); // Returns true
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rainbowRegex.test(british); // Returns true
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```
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# --instructions--
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Change the regex `favRegex` to match both the American English (favorite) and the British English (favourite) version of the word.
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# --hints--
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Your regex should use the optional symbol, `?`.
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```js
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favRegex.lastIndex = 0;
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assert(favRegex.source.match(/\?/).length > 0);
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```
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Your regex should match `"favorite"`
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```js
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favRegex.lastIndex = 0;
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assert(favRegex.test('favorite'));
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```
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Your regex should match `"favourite"`
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```js
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favRegex.lastIndex = 0;
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assert(favRegex.test('favourite'));
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```
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Your regex should not match `"fav"`
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```js
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favRegex.lastIndex = 0;
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assert(!favRegex.test('fav'));
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```
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# --seed--
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## --seed-contents--
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```js
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let favWord = "favorite";
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let favRegex = /change/; // Change this line
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let result = favRegex.test(favWord);
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```
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# --solutions--
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```js
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let favWord = "favorite";
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let favRegex = /favou?r/;
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let result = favRegex.test(favWord);
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```
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