60 lines
1.7 KiB
Markdown
60 lines
1.7 KiB
Markdown
# safe-regex2
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[](https://github.com/fastify/safe-regex2/actions/workflows/ci.yml)
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[](https://www.npmjs.com/package/safe-regex2)
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[](https://github.com/neostandard/neostandard)
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Detect potentially [catastrophic](http://regular-expressions.mobi/catastrophic.html) [exponential-time](http://perlgeek.de/blog-en/perl-tips/in-search-of-an-exponetial-regexp.html)
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regular expressions by limiting the [star height](https://en.wikipedia.org/wiki/Star_height) to 1.
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This is a fork of https://github.com/substack/safe-regex at 1.1.0.
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WARNING: This module has both false positives and false negatives.
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It is not meant as a full checker, but it detects basic cases.
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## Install
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```
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npm i safe-regex2
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```
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## Example
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``` js
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const safe = require('safe-regex2');
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const regex = process.argv.slice(2).join(' ');
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console.log(safe(regex));
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```
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```
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$ node safe.js '(x+x+)+y'
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false
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$ node safe.js '(beep|boop)*'
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true
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$ node safe.js '(a+){10}'
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false
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$ node safe.js '\blocation\s*:[^:\n]+\b(Oakland|San Francisco)\b'
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true
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```
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## Methods
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``` js
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const safe = require('safe-regex')
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```
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### const ok = safe(re, opts={})
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Returns a boolean indicating whether the regex `re` is safe
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and not possibly catastrophic.
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`re` can be a `RegExp` object or just a string.
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If `re` is a string and is an invalid regex, it returns `false`.
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* `opts.limit` - maximum number of allowed repetitions in the entire regex.
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Default: `25`.
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## License
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Licensed under [MIT](./LICENSE).
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