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Escape String RegExp

Escape String RegExp is a lightweight JavaScript utility that escapes RegExp special characters in strings, making them safe to use as literal text within regular expressions. It provides Unicode-safe escaping to prevent regex injection vulnerabilities when constructing regular expressions from user input or dynamic content.

Package Information

Package Name: escape-string-regexp
Package Type: npm
Language: JavaScript/TypeScript (ES Module with TypeScript definitions)
Installation: npm install escape-string-regexp

Core Imports

import escapeStringRegexp from 'escape-string-regexp';

TypeScript:

import escapeStringRegexp from 'escape-string-regexp';

Basic Usage

import escapeStringRegexp from 'escape-string-regexp';

// Escape a string for safe use in RegExp
const userInput = 'How much $ for a 🦄?';
const escapedString = escapeStringRegexp(userInput);
console.log(escapedString);
//=> 'How much \\$ for a 🦄\\?'

// Use the escaped string in a regular expression
const regex = new RegExp(escapedString);
console.log(regex.test(userInput)); // true

// Common use case: search for literal text in a larger string
const searchFor = '$.99';
const text = 'The price is $.99 today';
const searchRegex = new RegExp(escapeStringRegexp(searchFor), 'g');
console.log(text.match(searchRegex)); // ['$.99']

Capabilities

String Escaping

Escapes all RegExp special characters in a string to make it safe for literal use in regular expressions.

/**
 * Escape RegExp special characters in a string
 * @param string - The input string to escape
 * @returns The escaped string with special RegExp characters properly escaped
 * @throws TypeError when input is not a string
 */
function escapeStringRegexp(string: string): string;

Escaped Characters:

Special RegExp characters: |, \, {, }, (, ), [, ], ^, $, +, *, ?, .
Dash character: - (escaped as \x2d for Unicode pattern compatibility)

Error Handling:

Throws TypeError with message "Expected a string" when input is not a string

Usage Examples:

// Basic escaping of special characters
escapeStringRegexp('hello.world');
//=> 'hello\\.world'

escapeStringRegexp('user@domain.com');
//=> 'user@domain\\.com'

// Escaping complex patterns
escapeStringRegexp('[urgent] $100+ required');
//=> '\\[urgent\\] \\$100\\+ required'

// Unicode-safe dash escaping
escapeStringRegexp('foo-bar');
//=> 'foo\\x2dbar'

// Error handling
try {
  escapeStringRegexp(123);
} catch (error) {
  console.log(error.message); // "Expected a string"
}

// Common pattern: case-insensitive search
const searchTerm = 'Mr. Smith';
const text = 'Looking for mr. smith in the database';
const regex = new RegExp(escapeStringRegexp(searchTerm), 'i');
console.log(regex.test(text)); // true

Implementation Details:

Uses backslash escape (\\$&) for most special RegExp characters
Uses hex escape (\\x2d) for dash character to ensure compatibility with Unicode flag
Zero dependencies - pure JavaScript implementation
ES Module format with Node.js 12+ requirement

Security Considerations:

Prevents regex injection attacks when using user input in regular expressions
Safe for use with any Unicode input
Maintains compatibility with both PCRE and JavaScript regex engines