regexpu

library4.8.0jsnpmunverified

regexpu is a source code transpiler that enables the use of ES2015 Unicode regular expressions (the `u` flag) in ES5 environments. It rewrites regex literals with the `u` flag into equivalent ES5-compatible patterns, handling Unicode properties, escapes, and case folding. Current version 4.8.0 (stable) releases infrequently; major version bumps (e.g., 2.0.0) introduced breaking changes in module export paths. Key differentiators: it is the core engine behind Babel, Traceur, and other transpilers for Unicode regex; also ships `regexpu-core` for programmatic use. Supports Node >=6 and browsers via bundlers.

serialization

npm install regexpu

github ↗package ↗homepage ↗

INSTALL

IMPORT

SIG · REGEXPU

regexpu

serializationjavascriptv4.8.0

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'

✗ const rewritePattern = require('regexpu').rewritePattern

Before v2.0.0, the correct import was require('regexpu').rewritePattern; after v2.0.0, ESM-style named import is preferred. CommonJS users should use the new path.

default

✓ import regexpu from 'regexpu'

✗ const regexpu = require('regexpu')

Default export exists in ESM; CommonJS requires destructuring. ESM-only since v2.0.0?

rewritePattern (from regexpu-core)

✓ import { rewritePattern } from 'regexpu-core'

✗ const rewritePattern = require('regexpu').rewritePattern

The core module regexpu-core is the recommended way since v2.0.0; the main package now re-exports it.

Transpiles a Unicode regex pattern with the u flag to an ES5-compatible equivalent, demonstrating usage of rewritePattern with options.

import { rewritePattern } from 'regexpu-core'; // Transpile a regex with the u flag to ES5 const pattern = '\\p{ASCII_Hex_Digit}'; const flags = 'u'; const result = rewritePattern(pattern, flags); console.log(result); // '[A-Fa-f0-9]' // With support for Unicode properties const pattern2 = '\\p{Emoji}'; const flags2 = 'u'; const result2 = rewritePattern(pattern2, flags2, { unicodePropertyEscape: true }); console.log(result2); // '[...]'

Debug

Known issues

breakingBreaking change in v2.0.0: require('regexpu-core') is the new require('regexpu/rewrite-pattern')

fix

Update imports: use require('regexpu-core') or import { rewritePattern } from 'regexpu-core' instead of old require('regexpu').rewritePattern.

affects: >= 2.0.0

deprecatedUsing require('regexpu') directly may be deprecated; prefer regexpu-core submodule.

fix

Switch to require('regexpu-core') for the rewritePattern function.

affects: >= 2.0.0

gotchaThe package only transpiles the regex pattern string; it does not handle the regular expression literal syntax. Pass the pattern without delimiters.

fix

Ensure input is a string pattern (e.g., '\\p{ASCII_Hex_Digit}') not '/\\p{ASCII_Hex_Digit}/u'.

affects: >= 1.0.0

gotchaOptions object must be passed correctly: { unicodePropertyEscape: true } to enable Unicode property escapes (default false).

fix

Pass options as second or third argument to rewritePattern.

affects: >= 3.0.0

Errors

Common errors & fixes

require is not defined

Trying to use CommonJS require in an ESM module (e.g., .mjs file or type:module).

fix

Use import statements: import { rewritePattern } from 'regexpu-core';

Cannot find module 'regexpu' or 'regexpu-core'

Module not installed or incorrect import path.

fix

Install the correct package: npm install regexpu --save (or regexpu-core if using core).

rewritePattern is not a function

Import destructuring error; default export vs named export confusion.

fix

Use named import: import { rewritePattern } from 'regexpu-core';

Upgrade

Version history

4.8.0latest on npm

Audit

Dependencies

No dependency data recorded yet.

Agent activity

2 hits · last 30 days

node

Resources

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

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

homepagehttps://mths.be/regexpu ↗