escape-string-regexp 4.0.0: escape special regex characters from string

Clean-room public code sample — generation instructions

Write a brand-new, minimal, self-contained code sample in this clean-room directory.
Do not copy, paraphrase, or reference any existing project source. Work only from this spec.

A csx.json manifest scaffold already exists. Do not recreate it from memory. Preserve its case.goal, packages and symbols; fill its empty case.contract with exact assertions and correct its environment, commands and verifierAdapter for the files you generate.

Goal: escape special regex characters from string
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/escape-string-regexp@4.0.0
Demonstrate these symbols/APIs:
  - escapeStringRegexp
Constraints:
  - executionContext: node
Required runtime conditions:
  - ecosystem: npm
  - language: javascript
  - moduleSystem: cjs
  - packageManager: npm@10.9.8
  - runtime: node@22.23.2

Rules:
  - One focused purpose; the smallest project that proves the goal.
  - Include a contract test (test/contract.*) that runs OFFLINE and exits 0 exactly when the goal behavior works.
  - Pin every dependency with a lockfile so resolution is reproducible.
  - No secrets, credentials, or tokens. No real URLs (only example.com or localhost). No absolute paths.
  - No personal names, emails, company names, or project identifiers of any kind.
  - No binaries and no generated output (node_modules, dist, target, venv, .git, .env).
  - Keep it under 200 files and 256KB packed.

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{
  "name": "sample-escape-string-regexp",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-escape-string-regexp",
      "version": "1.0.0",
      "dependencies": {
        "escape-string-regexp": "4.0.0"
      }
    },
    "node_modules/escape-string-regexp": {
      "version": "4.0.0",
      "resolved": "https://registry.npmjs.org/escape-string-regexp/-/escape-string-regexp-4.0.0.tgz",
      "integrity": "sha512-TtpcNJ3XAzx3Gq8sWRzJaVajRs0uVxA2YAkdb1jm2YkPz4G6egUFAyA3n5vtEIZefPk5Wa4UXbKuS5fKkJWdgA==",
      "license": "MIT",
      "engines": {
        "node": ">=10"
      },
      "funding": {
        "url": "https://github.com/sponsors/sindresorhus"
      }
    }
  }
}

{
  "name": "sample-escape-string-regexp",
  "version": "1.0.0",
  "type": "module",
  "private": true,
  "dependencies": {
    "escape-string-regexp": "4.0.0"
  }
}

{
  "schemaVersion": 1,
  "goal": "escape special regex characters from string",
  "kind": "HOW",
  "packages": [
    "pkg:npm/escape-string-regexp@4.0.0"
  ],
  "symbols": [
    "escapeStringRegexp"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "packageManager": "npm@10.9.8",
    "runtime": "node@22.23.2"
  }
}

import assert from 'node:assert/strict';
import escapeStringRegexp from 'escape-string-regexp';

// 1. Verify export is a callable function
assert.equal(typeof escapeStringRegexp, 'function', 'escapeStringRegexp should be a function');

// 2. Verify escaping all standard regex metacharacters
const specialCharacters = '|\\{}()[]^$+*?.';
const escapedCharacters = escapeStringRegexp(specialCharacters);
assert.equal(
  escapedCharacters,
  '\\|\\\\\\{\\}\\(\\)\\[\\]\\^\\$\\+\\*\\?\\.',
  'all regex special characters must be escaped with a backslash'
);

// 3. Verify escaping dash character as \x2d
const withDash = escapeStringRegexp('hello-world');
assert.equal(withDash, 'hello\\x2dworld', 'dash character must be escaped as \\x2d');

// 4. Verify escaped string matches literally when used in new RegExp
const testInput = 'Price: $9.99 (50% off) [item #1] + bonus!';
const escapedPattern = escapeStringRegexp(testInput);
const regex = new RegExp(`^${escapedPattern}$`);

assert.ok(regex.test(testInput), 'RegExp should match the exact literal input string');
assert.ok(!regex.test('Price: $9999 (50% off) [item #1] + bonus!'), 'RegExp should not treat unescaped characters as wildcards');

// 5. Verify non-string inputs throw TypeError
assert.throws(
  () => escapeStringRegexp(123),
  {
    name: 'TypeError',
    message: 'Expected a string',
  },
  'calling with number should throw TypeError'
);

assert.throws(
  () => escapeStringRegexp(null),
  {
    name: 'TypeError',
    message: 'Expected a string',
  },
  'calling with null should throw TypeError'
);

assert.throws(
  () => escapeStringRegexp(undefined),
  {
    name: 'TypeError',
    message: 'Expected a string',
  },
  'calling with undefined should throw TypeError'
);

// 6. Verify empty string returns empty string
assert.equal(escapeStringRegexp(''), '', 'empty string input should return empty string');

console.log('Contract test passed successfully for escape-string-regexp');