lodash.debounce 4.0.8: debounce

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/lodash.debounce@4.0.8
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/lodash.debounce@4.0.8
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.

{"case":{"caseId":"case:sha256:776815fbcc3eb6ce9bec080924cf87673c8773b5640261a854c86c703ede3222","constraints":{"executionContext":"node"},"contract":["debounce delays invoking func until after wait milliseconds have elapsed and collapses multiple calls","debounce passes arguments from the last invocation to func","debounce cancel method cancels delayed func invocations","debounce flush method immediately executes delayed func invocation and returns its result","debounce leading option invokes func on the leading edge of the timeout","debounce maxWait option forces func invocation after maximum delay"],"goal":"verify pkg:npm/lodash.debounce@4.0.8","kind":"HOW","packages":["pkg:npm/lodash.debounce@4.0.8"],"schemaVersion":1,"symbols":["debounce"]},"contractCommand":["node","test/contract.mjs"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"npm","executionContext":"node","language":"javascript","libc":"glibc","libcVersion":"2.39","moduleSystem":"cjs","os":"linux","osVersionBucket":"24","packageManager":"npm","packageManagerVersion":"10.9.8","runtime":"node","runtimeVersion":"22.23.2","schemaVersion":1},"license":"MIT-0","packages":["pkg:npm/lodash.debounce@4.0.8"],"schemaVersion":1,"subject":"pkg:npm/lodash.debounce@4.0.8","symbols":["debounce"],"verifierAdapter":"node-typescript@1"}

const debounce = require('lodash.debounce');

/**
 * Creates a debounced function that delays invoking func until after wait milliseconds.
 *
 * @param {Function} func The function to debounce.
 * @param {number} [wait=0] The number of milliseconds to delay.
 * @param {Object} [options={}] The options object.
 * @returns {Function} Returns the new debounced function.
 */
function createDebouncedFunction(func, wait = 0, options = {}) {
  return debounce(func, wait, options);
}

module.exports = {
  debounce,
  createDebouncedFunction,
};

{
  "name": "sample-lodash-debounce",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-lodash-debounce",
      "version": "1.0.0",
      "license": "MIT-0",
      "dependencies": {
        "lodash.debounce": "4.0.8"
      }
    },
    "node_modules/lodash.debounce": {
      "version": "4.0.8",
      "resolved": "https://registry.npmjs.org/lodash.debounce/-/lodash.debounce-4.0.8.tgz",
      "integrity": "sha512-FT1yDzDYEoYWhnSGnpE/4Kj1fLZkDFyqRb7fNt6FdYOSxlUWAtp42Eh6Wb0rGIv/m9Bgo7x4GhQbm5Ys4SG5ow==",
      "license": "MIT"
    }
  }
}

{
  "name": "sample-lodash-debounce",
  "version": "1.0.0",
  "description": "Clean-room sample verifying pkg:npm/lodash.debounce@4.0.8 functionality",
  "main": "index.js",
  "license": "MIT-0",
  "dependencies": {
    "lodash.debounce": "4.0.8"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify pkg:npm/lodash.debounce@4.0.8",
  "kind": "HOW",
  "packages": [
    "pkg:npm/lodash.debounce@4.0.8"
  ],
  "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';
import { setTimeout as sleep } from 'node:timers/promises';
import debounce from 'lodash.debounce';
import { createDebouncedFunction } from '../index.js';

async function runContractTests() {
  // 1. Delays execution until wait time elapses and collapses multiple calls
  let callCount = 0;
  let lastArg = null;
  const debounced = createDebouncedFunction((arg) => {
    callCount += 1;
    lastArg = arg;
  }, 30);

  debounced('call 1');
  debounced('call 2');
  debounced('call 3');

  assert.strictEqual(callCount, 0, 'debounce must delay execution');
  await sleep(60);
  assert.strictEqual(callCount, 1, 'debounce must collapse multiple calls within window into single execution');
  assert.strictEqual(lastArg, 'call 3', 'debounce must receive arguments from the last invocation');

  // 2. Supports cancel method
  let cancelTargetCount = 0;
  const cancelable = debounce(() => {
    cancelTargetCount += 1;
  }, 30);

  cancelable();
  cancelable.cancel();
  await sleep(60);
  assert.strictEqual(cancelTargetCount, 0, 'cancel method must prevent delayed execution');

  // 3. Supports flush method
  let flushTargetCount = 0;
  const flushable = debounce(() => {
    flushTargetCount += 1;
    return 'flushed';
  }, 100);

  flushable();
  assert.strictEqual(flushTargetCount, 0, 'function not yet called before flush');
  const result = flushable.flush();
  assert.strictEqual(flushTargetCount, 1, 'flush method must immediately execute pending invocation');
  assert.strictEqual(result, 'flushed', 'flush method must return the result of the invocation');

  // 4. Supports leading and trailing options
  let leadingCount = 0;
  const leadingDebounced = debounce(() => {
    leadingCount += 1;
  }, 30, { leading: true, trailing: false });

  leadingDebounced();
  assert.strictEqual(leadingCount, 1, 'leading option must trigger immediate invocation on first call');
  leadingDebounced();
  await sleep(60);
  assert.strictEqual(leadingCount, 1, 'trailing false must prevent delayed second invocation');

  // 5. Supports maxWait option
  let maxWaitCount = 0;
  const maxWaitDebounced = debounce(() => {
    maxWaitCount += 1;
  }, 50, { maxWait: 50 });

  maxWaitDebounced();
  await sleep(25);
  maxWaitDebounced();
  await sleep(35);
  assert.strictEqual(maxWaitCount, 1, 'maxWait option must force execution even if calls continue');
  await sleep(60);

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

runContractTests();