regexpu-core

    2.0.0 • Public • Published

    regexpu-core Build status Code coverage status Dependency status

    regexpu is a source code transpiler that enables the use of ES6 Unicode regular expressions in JavaScript-of-today (ES5).

    regexpu-core contains regexpu’s core functionality, i.e. rewritePattern(pattern, flag), which enables rewriting regular expressions that make use of the ES6 u flag into equivalent ES5-compatible regular expression patterns.

    Installation

    To use regexpu-core programmatically, install it as a dependency via npm:

    npm install regexpu-core --save-dev

    Then, require it:

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

    API

    This module exports a single function named rewritePattern.

    rewritePattern(pattern, flags)

    This function takes a string that represents a regular expression pattern as well as a string representing its flags, and returns an ES5-compatible version of the pattern.

    rewritePattern('foo.bar', 'u');
    // → 'foo(?:[\\0-\\t\\x0B\\f\\x0E-\\u2027\\u202A-\\uD7FF\\uDC00-\\uFFFF]|[\\uD800-\\uDBFF][\\uDC00-\\uDFFF]|[\\uD800-\\uDBFF])bar'
     
    rewritePattern('[\\u{1D306}-\\u{1D308}a-z]', 'u');
    // → '(?:[a-z]|\\uD834[\\uDF06-\\uDF08])'
     
    rewritePattern('[\\u{1D306}-\\u{1D308}a-z]', 'ui');
    // → '(?:[a-z\\u017F\\u212A]|\\uD834[\\uDF06-\\uDF08])'

    regexpu-core can rewrite non-ES6 regular expressions too, which is useful to demonstrate how their behavior changes once the u and i flags are added:

    // In ES5, the dot operator only matches BMP symbols:
    rewritePattern('foo.bar');
    // → 'foo(?:[\\0-\\t\\x0B\\f\\x0E-\\u2027\\u202A-\\uFFFF])bar'
     
    // But with the ES6 `u` flag, it matches astral symbols too:
    rewritePattern('foo.bar', 'u');
    // → 'foo(?:[\\0-\\t\\x0B\\f\\x0E-\\u2027\\u202A-\\uD7FF\\uDC00-\\uFFFF]|[\\uD800-\\uDBFF][\\uDC00-\\uDFFF]|[\\uD800-\\uDBFF])bar'

    rewritePattern uses regjsgen, regjsparser, and regenerate as internal dependencies.

    Author

    twitter/mathias
    Mathias Bynens

    License

    regexpu-core is available under the MIT license.

    Install

    npm i regexpu-core@2.0.0

    Version

    2.0.0

    License

    MIT

    Last publish

    Collaborators

    • mathias
    • jridgewell
    • nicolo-ribaudo
    • google-wombot