17 lines
940 B
Markdown
17 lines
940 B
Markdown
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---
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title: Positive and Negative Lookahead
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---
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## Positive and Negative Lookahead
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- Remeber to use 2 `lookaheads` to check the patterns in the string. The first `lookahead` is very similar to that given in the example - '(?=\w{3,6})' - only the `lower-number` 3 is too low for our test cases, and an `upper-number` is completely unneccesarry. This first `lookahead` is only used to find a string consisting of a certain amount of characters. A second `lookahead` must be used to check for consecutive numerical values at the end of the string.
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- The second `lookahead` is also similar to that given in the example - `(?=\D*\d)` - however, this expression too must be modified to pass all test cases. Remember to specify the exact amount of numbers you want to appear at the end of the string.
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## Solution :
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```javascript
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let sampleWord = "astronaut";
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let pwRegex = /(?=\w{5,})(?=\D*\d{2})/;
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let result = pwRegex.test(sampleWord);
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```
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