string-width 5.1.2

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: verify pkg:npm/string-width@5.1.2
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/string-width@5.1.2

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.

{"case":{"caseId":"case:sha256:1776d7ae384548407d3cb7d178c7818f18abbbf8de1bb4d3f59594d3b9eb868a","contract":["stringWidth calculates visual display width for ASCII characters","stringWidth counts fullwidth CJK characters as width 2","stringWidth counts emoji characters as width 2","stringWidth ignores ANSI escape sequences when computing visual width","stringWidth handles ambiguous width characters according to ambiguousIsNarrow option","stringWidth returns 0 for empty string"],"goal":"verify pkg:npm/string-width@5.1.2","kind":"HOW","packages":["pkg:npm/string-width@5.1.2"],"schemaVersion":1},"contractCommand":["node","test/contract.mjs"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"npm","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"npm","schemaVersion":1},"license":"MIT-0","packages":["pkg:npm/string-width@5.1.2"],"schemaVersion":1,"subject":"pkg:npm/string-width@5.1.2","verifierAdapter":"node-typescript@1"}

import stringWidth from 'string-width';

/**
 * Calculates visual display width of a string.
 *
 * @param {string} text - The input string to measure.
 * @param {object} [options] - Options for width calculation.
 * @param {boolean} [options.ambiguousIsNarrow] - Whether ambiguous characters count as width 1.
 * @returns {number} Visual column width.
 */
export function getVisualWidth(text, options) {
  return stringWidth(text, options);
}

export default stringWidth;

{
  "name": "sample-string-width",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-string-width",
      "version": "1.0.0",
      "license": "MIT-0",
      "dependencies": {
        "string-width": "5.1.2"
      }
    },
    "node_modules/ansi-regex": {
      "version": "6.3.0",
      "resolved": "https://registry.npmjs.org/ansi-regex/-/ansi-regex-6.3.0.tgz",
      "integrity": "sha512-WpDfL7NO6j7tH88IDBNVdUJxDh9nmCteAVW9dsep846XdwF4naCBK+/tGLX3KJgcpgMRXCFlTM2hKGoK9FsdrQ==",
      "license": "MIT",
      "engines": {
        "node": ">=12"
      },
      "funding": {
        "url": "https://github.com/chalk/ansi-regex?sponsor=1"
      }
    },
    "node_modules/eastasianwidth": {
      "version": "0.2.0",
      "resolved": "https://registry.npmjs.org/eastasianwidth/-/eastasianwidth-0.2.0.tgz",
      "integrity": "sha512-I88TYZWc9XiYHRQ4/3c5rjjfgkjhLyW2luGIheGERbNQ6OY7yTybanSpDXZa8y7VUP9YmDcYa+eyq4ca7iLqWA==",
      "license": "MIT"
    },
    "node_modules/emoji-regex": {
      "version": "9.2.2",
      "resolved": "https://registry.npmjs.org/emoji-regex/-/emoji-regex-9.2.2.tgz",
      "integrity": "sha512-L18DaJsXSUk2+42pv8mLs5jJT2hqFkFE4j21wOmgbUqsZ2hL72NsUU785g9RXgo3s0ZNgVl42TiHp3ZtOv/Vyg==",
      "license": "MIT"
    },
    "node_modules/string-width": {
      "version": "5.1.2",
      "resolved": "https://registry.npmjs.org/string-width/-/string-width-5.1.2.tgz",
      "integrity": "sha512-HnLOCR3vjcY8beoNLtcjZ5/nxn2afmME6lhrDrebokqMap+XbeW8n9TXpPDOqdGK5qcI3oT0GKTW6wC7EMiVqA==",
      "license": "MIT",
      "dependencies": {
        "eastasianwidth": "^0.2.0",
        "emoji-regex": "^9.2.2",
        "strip-ansi": "^7.0.1"
      },
      "engines": {
        "node": ">=12"
      },
      "funding": {
        "url": "https://github.com/sponsors/sindresorhus"
      }
    },
    "node_modules/strip-ansi": {
      "version": "7.2.0",
      "resolved": "https://registry.npmjs.org/strip-ansi/-/strip-ansi-7.2.0.tgz",
      "integrity": "sha512-yDPMNjp4WyfYBkHnjIRLfca1i6KMyGCtsVgoKe/z1+6vukgaENdgGBZt+ZmKPc4gavvEZ5OgHfHdrazhgNyG7w==",
      "license": "MIT",
      "dependencies": {
        "ansi-regex": "^6.2.2"
      },
      "engines": {
        "node": ">=12"
      },
      "funding": {
        "url": "https://github.com/chalk/strip-ansi?sponsor=1"
      }
    }
  }
}

{
  "name": "sample-string-width",
  "version": "1.0.0",
  "description": "Clean-room sample verifying string-width functionality",
  "type": "module",
  "main": "index.js",
  "license": "MIT-0",
  "dependencies": {
    "string-width": "5.1.2"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify pkg:npm/string-width@5.1.2",
  "kind": "HOW",
  "packages": [
    "pkg:npm/string-width@5.1.2"
  ]
}

import assert from 'node:assert';
import stringWidth, { getVisualWidth } from '../index.js';

// 1. ASCII characters: single width
assert.strictEqual(stringWidth('hello'), 5, 'ASCII characters should have width 1 per char');
assert.strictEqual(getVisualWidth('world!'), 6, 'Wrapper function should match stringWidth');

// 2. CJK / Fullwidth characters: double width
assert.strictEqual(stringWidth('你好'), 4, 'CJK characters should have width 2');
assert.strictEqual(stringWidth('한글'), 4, 'Korean characters should have width 2');
assert.strictEqual(stringWidth('テスト'), 6, 'Japanese katakana should have width 2 per char');

// 3. Emoji: width 2
assert.strictEqual(stringWidth('🚀'), 2, 'Emoji character should have width 2');
assert.strictEqual(stringWidth('🎉'), 2, 'Emoji character should have width 2');

// 4. ANSI escape codes: stripped, width 0 for escape sequences
assert.strictEqual(stringWidth('\u001B[31mred\u001B[39m'), 3, 'ANSI color codes should not add to visual width');
assert.strictEqual(stringWidth('\u001B[1mbold\u001B[22m'), 4, 'ANSI style codes should not add to visual width');

// 5. Ambiguous width characters
// By default ambiguousIsNarrow is true -> width 1
assert.strictEqual(stringWidth('α'), 1, 'Ambiguous char defaults to width 1');
assert.strictEqual(stringWidth('α', { ambiguousIsNarrow: true }), 1, 'ambiguousIsNarrow: true gives width 1');
assert.strictEqual(stringWidth('α', { ambiguousIsNarrow: false }), 2, 'ambiguousIsNarrow: false gives width 2');

// 6. Empty and control characters
assert.strictEqual(stringWidth(''), 0, 'Empty string should have width 0');
assert.strictEqual(stringWidth('\0'), 0, 'Null character should have width 0');

console.log('All contract assertions passed.');