sprintf-js 1.1.3: vsprintf

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 vsprintf in pkg:npm/sprintf-js@1.1.3
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/sprintf-js@1.1.3
Demonstrate these symbols/APIs:
  - vsprintf

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:sha256:7d51b3521f26595ed76fdc7827701a12ba4df0adaf293bb78404644e85c0c4be","contract":["vsprintf formats strings by interpolating an array of positional values into placeholder specifiers","vsprintf formats numbers with specified width, zero padding, sign, and decimal precision","vsprintf supports alternative base conversions including hexadecimal, binary, and octal","vsprintf supports explicit argument indexing to rearrange argument order","vsprintf formats named object properties passed within an array argument","vsprintf serializes complex JavaScript objects to JSON with the %j specifier","vsprintf pads strings with custom fill characters and left or right alignment","vsprintf throws an error when format strings contain syntax errors or missing required arguments"],"goal":"verify vsprintf in pkg:npm/sprintf-js@1.1.3","kind":"HOW","packages":["pkg:npm/sprintf-js@1.1.3"],"schemaVersion":1,"symbols":["vsprintf"]},"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/sprintf-js@1.1.3"],"schemaVersion":1,"subject":"pkg:npm/sprintf-js@1.1.3","symbols":["vsprintf"],"verifierAdapter":"node-typescript@1"}

{
  "name": "sample-3754283252",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-3754283252",
      "version": "1.0.0",
      "license": "ISC",
      "dependencies": {
        "sprintf-js": "^1.1.3"
      }
    },
    "node_modules/sprintf-js": {
      "version": "1.1.3",
      "resolved": "https://registry.npmjs.org/sprintf-js/-/sprintf-js-1.1.3.tgz",
      "integrity": "sha512-Oo+0REFV59/rz3gfJNKQiBlwfHaSESl1pcGyABQsnnIfWOFt6JNj5gCog2U6MLZ//IGYD+nA8nI+mTShREReaA==",
      "license": "BSD-3-Clause"
    }
  }
}

{
  "name": "sample-sprintf-js",
  "version": "1.0.0",
  "type": "module",
  "private": true,
  "license": "MIT-0",
  "scripts": {
    "test": "node test/contract.mjs"
  },
  "dependencies": {
    "sprintf-js": "1.1.3"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify vsprintf in pkg:npm/sprintf-js@1.1.3",
  "kind": "HOW",
  "packages": [
    "pkg:npm/sprintf-js@1.1.3"
  ],
  "symbols": [
    "vsprintf"
  ]
}

import sprintfJs from 'sprintf-js';

const { vsprintf, sprintf } = sprintfJs;

/**
 * Format a string with an array of arguments using vsprintf.
 * @param {string} format Format specification string
 * @param {Array<any>} args Array of arguments
 * @returns {string} Formatted string
 */
export function formatWithArray(format, args) {
  return vsprintf(format, args);
}

/**
 * Format a string with named arguments using vsprintf.
 * @param {string} format Format specification string with named keys
 * @param {Record<string, any>} data Named parameters object
 * @returns {string} Formatted string
 */
export function formatWithNamed(format, data) {
  return vsprintf(format, [data]);
}

export { vsprintf, sprintf };
export default vsprintf;

import assert from 'node:assert/strict';
import { vsprintf, sprintf, formatWithArray, formatWithNamed } from '../src/index.mjs';

// 1. vsprintf formats strings by interpolating an array of positional values into placeholder specifiers
{
  const result = vsprintf('%s is %d years old', ['Alice', 30]);
  assert.equal(result, 'Alice is 30 years old');

  const helperResult = formatWithArray('Hello, %s!', ['world']);
  assert.equal(helperResult, 'Hello, world!');
}

// 2. vsprintf formats numbers with specified width, zero padding, sign, and decimal precision
{
  const pi = vsprintf('%.2f', [3.14159265]);
  assert.equal(pi, '3.14');

  const paddedInt = vsprintf('%05d', [42]);
  assert.equal(paddedInt, '00042');

  const signs = vsprintf('%+d and %+d', [10, -10]);
  assert.equal(signs, '+10 and -10');
}

// 3. vsprintf supports alternative base conversions including hexadecimal, binary, and octal
{
  const hex = vsprintf('%x / %X', [255, 255]);
  assert.equal(hex, 'ff / FF');

  const bin = vsprintf('%b', [13]);
  assert.equal(bin, '1101');

  const oct = vsprintf('%o', [64]);
  assert.equal(oct, '100');
}

// 4. vsprintf supports explicit argument indexing to rearrange argument order
{
  const reordered = vsprintf('%2$s before %1$s', ['first', 'second']);
  assert.equal(reordered, 'second before first');
}

// 5. vsprintf formats named object properties passed within an array argument
{
  const userGreeting = vsprintf('User %(name)s logged in %(count)d times', [{ name: 'Bob', count: 5 }]);
  assert.equal(userGreeting, 'User Bob logged in 5 times');

  const helperNamed = formatWithNamed('Item: %(item)s, Price: $%(price).2f', { item: 'Widget', price: 9.99 });
  assert.equal(helperNamed, 'Item: Widget, Price: $9.99');
}

// 6. vsprintf serializes complex JavaScript objects to JSON with the %j specifier
{
  const jsonStr = vsprintf('Data: %j', [{ id: 101, active: true }]);
  assert.equal(jsonStr, 'Data: {"id":101,"active":true}');
}

// 7. vsprintf pads strings with custom fill characters and left or right alignment
{
  const rightPadded = vsprintf("%'#-8s", ['pad']);
  assert.equal(rightPadded, 'pad#####');

  const leftPadded = vsprintf("%'#8s", ['pad']);
  assert.equal(leftPadded, '#####pad');
}

// 8. vsprintf throws an error when format strings contain syntax errors or missing required arguments
{
  assert.throws(() => vsprintf('%d', []), /\[sprintf\]/);
  assert.throws(() => vsprintf('%', ['test']), /\[sprintf\]/);
}

console.log('Contract assertions passed.');