clone-regexp

What is clone-regexp?

The clone-regexp npm package is designed to clone regular expressions with the option to modify their properties such as flags, source, and lastIndex. This can be useful when you need to reuse a regular expression with slight variations or reset its state without affecting the original regex.

What are clone-regexp's main functionalities?

Cloning a regular expression

This feature allows you to create a copy of an existing regular expression. The cloned regex will have the same source and flags as the original.

const cloneRegexp = require('clone-regexp');
const regex = /[a-z]/gi;
const clonedRegex = cloneRegexp(regex);
console.log(clonedRegex); // Output: /[a-z]/gi

Modifying flags

This feature allows you to clone a regular expression and modify its flags. In this example, the 'i' flag is removed, and the 'm' flag is added.

const cloneRegexp = require('clone-regexp');
const regex = /[a-z]/gi;
const clonedRegex = cloneRegexp(regex, {flags: 'gm'});
console.log(clonedRegex); // Output: /[a-z]/gm

Changing the lastIndex

This feature allows you to clone a regular expression and set the lastIndex property. This is useful when you want to reset the state of the regex for a new search.

const cloneRegexp = require('clone-regexp');
const regex = /[a-z]/gi;
regex.lastIndex = 10;
const clonedRegex = cloneRegexp(regex, {lastIndex: 0});
console.log(clonedRegex.lastIndex); // Output: 0

Other packages similar to clone-regexp

regexp-clone

The regexp-clone package provides similar functionality to clone-regexp by allowing users to clone regular expressions. It preserves the source, flags, and lastIndex of the original regex. The main difference is in the implementation and possibly in the specific features or options provided by each package.

clone

The clone package is a more general utility for cloning objects, arrays, dates, and regular expressions in JavaScript. While it can clone regular expressions like clone-regexp, it is not specialized for regex cloning and does not provide options to modify the cloned regex's properties.

README

clone-regexp

Clone and modify a RegExp instance

Install

$ npm install clone-regexp

Usage

import cloneRegexp from 'clone-regexp';

const regex = /[a-z]/gi;

cloneRegexp(regex);
//=> /[a-z]/gi

cloneRegexp(regex) === regex;
//=> false

cloneRegexp(regex, {global: false});
//=> /[a-z]/i

cloneRegexp(regex, {multiline: true});
//=> /[a-z]/gim

cloneRegexp(regex, {source: 'unicorn'});
//=> /unicorn/gi

API

cloneRegexp(regexp, options?)

regex

Type: RegExp

Regex to clone.

options

Type: object
Properties: source global ignoreCase multiline dotAll sticky unicode lastIndex

Optionally modify the cloned RegExp instance.