regexpu-core

library6.4.0jsnpmunverified

regexpu-core is the core module of regexpu, a transpiler that converts ES2015 Unicode regular expressions (with the `u` and `v` flags) into ES5-compatible patterns. Current stable version is 6.4.0. It supports features like Unicode property escapes, dotAll flag, named capture groups, and the `v` flag (unicodeSetsFlag), with options to either pass through or transform them. Released on npm with TypeScript types, it has a steady release cadence, updated for Unicode 15.1. Key differentiator: focused on core regexp rewriting without the full regexpu CLI, used by Babel and other tools.

serialization

npm install regexpu-core

github ↗package ↗homepage ↗

INSTALL

IMPORT

SIG · REGEXPU-CORE

regexpu-core

serializationjavascriptv6.4.0

harness data pending

Install & Compatibility

Where this runs

No compatibility data collected yet for this library.

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

rewritePattern

✓ import rewritePattern from 'regexpu-core'

✗ const rewritePattern = require('regexpu-core')

Default export; ESM and CJS both supported. In CJS, require returns the function directly.

rewritePattern (named)

✓ import { rewritePattern } from 'regexpu-core'

✗ import rewritePattern from 'regexpu-core'

Named export also available since v5.1.0; both named and default exports are the same function.

types

✓ import type { RewritePatternOptions } from 'regexpu-core'

✗ import { RewritePatternOptions } from 'regexpu-core'

Use `import type` for TypeScript interfaces to avoid runtime import.

Shows basic usage of rewritePattern to transpile a Unicode property escape regex into ES5-compatible pattern.

import rewritePattern from 'regexpu-core'; // Transform a Unicode regex with 'u' flag to ES5 const pattern = '\\p{ASCII_Hex_Digit}+'; const flags = 'u'; const result = rewritePattern(pattern, flags, { unicodePropertyEscapes: 'transform', unicodeFlag: 'transform', }); console.log(result); // E.g.: '(?:[0-9A-Fa-f])+'

Debug

Known issues

breakingv6.0.0: Always enable unicodeSetsFlag parsing. Removed option to disable 'v' flag support.

fix

Remove any setting that disables 'v' flag; pattern is always parsed with 'v' flag support.

affects: >=6.0.0 <6.0.0

deprecatedThe 'useUnicodeFlag' option is deprecated since v5.0.0.

fix

Replace 'useUnicodeFlag' with 'unicodeFlag' option.

affects: >=5.0.0 <5.0.0

gotchaWhen using CommonJS require, the default export is the function, not an object.

fix

Use `const rewritePattern = require('regexpu-core');` not `require('...').rewritePattern`.

affects: >=4.0.0

gotchaThe 'unicodeFlag' option must be 'transform' to actually transform; false leaves it as-is.

fix

Set `unicodeFlag: 'transform'` explicitly to get ES5-compatible output.

affects: >=5.0.0

gotchaNamed capture groups are not transformed by default; must set 'namedGroups' option.

fix

Pass `namedGroups: 'transform'` option to compile named groups.

affects: >=5.0.0

Errors

Common errors & fixes

TypeError: rewritePattern is not a function

Using named import when default export expected in CJS.

fix

Use `const rewritePattern = require('regexpu-core');`

Can't find module 'regexpu-core/data/character-class-escape-sets'

Importing internal modules directly, not part of public API.

fix

Do not import from internal paths; use only 'regexpu-core'.

TypeScript error: 'RewritePatternOptions' is a type and must be imported using a type-only import

Using regular import for a type-only export.

fix

Use `import type { RewritePatternOptions } from 'regexpu-core';`

Upgrade

Version history

6.4.0latest on npm

Audit

Dependencies

No dependency data recorded yet.

Agent activity

4 hits · last 30 days

node

Resources

githubhttps://github.com/mathiasbynens/regexpu-core ↗

packagehttps://www.npmjs.com/package/regexpu-core ↗

homepagehttps://mths.be/regexpu ↗