How to test a regex in JavaScript?

Use the built-in `RegExp.prototype.test()` method. For example: `/abc/.test('abcde')`. It returns `true` or `false`.

Does JavaScript support lookbehind?

Yes, modern browsers (Chrome 62+, Node 8.10+) support lookbehind assertions. Syntax: `(?<=prefix)match` for positive lookbehind.

How to replace all occurrences of a string in JS regex?

Use the global `g` flag with `replace()`. E.g., `str.replace(/foo/g, 'bar')`. In modern JS, you can also use `replaceAll('foo', 'bar')` without regex.

What is the \b anchor in JavaScript regex?

`\b` matches a word boundary. It allows you to match whole words only, e.g., `/\bcat\b/` matches 'cat' but not 'scattering'.

How do I use named capture groups in JavaScript?

ES2018 introduced named groups. Use `(? ...)` to define them, and access them via `result.groups.name`. Example: `/(? \d{4})/`.

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Q: How to replace all occurrences of a string in JS regex?

Use the global `g` flag with `replace()`. E.g., `str.replace(/foo/g, 'bar')`. In modern JS, you can also use `replaceAll('foo', 'bar')` without regex.

Q: What is the \b anchor in JavaScript regex?

`\b` matches a word boundary. It allows you to match whole words only, e.g., `/\bcat\b/` matches 'cat' but not 'scattering'.

Q: How do I use named capture groups in JavaScript?

ES2018 introduced named groups. Use `(? ...)` to define them, and access them via `result.groups.name`. Example: `/(? \d{4})/`.

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