52 lines
1.3 KiB
Markdown
52 lines
1.3 KiB
Markdown
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---
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title: Reuse Patterns Using Capture Groups
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---
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## Reuse Patterns Using Capture Group
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## Hint 1:
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Given code below:
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```javascript
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let testString = "test test test ";
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let reRegex =/(test)\s\1/;
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let result = reRegex.test(testString);
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```
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`result` will match only `test test` because `\1` in this example stands for the same text as most recently matched by the 1st capturing group `(test)`.
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If we were to lierally translate the regex, it would look something like this:
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```js
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let re = /(test)\s\1;
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let literalRe = /test\stest;
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```
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Both `rea` and `literalRe` would match the same thing.
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## Hint 2:
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Given the code below:
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```javascript
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let testString = "test test test ";
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let reRegex =/(test)(\s)\1\2\1/;
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let result = reRegex.test(testString);
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```
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will match whole `test test test` because:
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`\1` repeats (test)
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`\2` repeats (\s)
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## Hint 3:
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The code below:
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```javascript
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let testString = "test test test test test test";
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let reRegex =/(test)(\s)\1\2\1/g;
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let result = reRegex.test(testString);
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```
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because we used `\g`, our Regex doesn't return after first full match (`test test test`) and matched all repetitions.
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## Spoiler Alert - Solution Ahead!
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## Solution:
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```javascript
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let repeatNum = "42 42 42";
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let reRegex = /^(\d+)\s\1\s\1$/;
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let result = reRegex.test(repeatNum);
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```
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