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Works in Node.js, browsers, Deno and Bun.","maintainers":[{"name":"onury","email":"onur@cutepilot.com"}],"readme":"# perfy\n\n

\n \"build\"\n \"coverage\"\n \"mutation\n \"version\"\n \"downloads\"\n \"zero\n \"ESM\"\n \"TS\"\n \"license\"\n

\n\n> This module is **ESM** 🔆. Please [**read this**](https://gist.github.com/onury/d3f3d765d7db2e8b2d050d14315f2ac7).\n\nA tiny, **zero-dependency** utility for measuring code execution time in **high-resolution real time** — named timers, one-shot `exec()` wrappers, and a rich elapsed-time result. Runs in **Node.js, browsers, Deno and Bun**.\n\n```ts\nimport { perfy } from 'perfy';\n\nperfy.start('loop');\n// ...heavy work...\nconsole.log(perfy.end('loop').time); // -> 1.235 (sec.)\n```\n\n> [!NOTE]\n> Perfy picks the **most precise clock available**: `process.hrtime.bigint()` on Node.js (exact integer nanoseconds), falling back to `performance.now()` elsewhere. The elapsed time is computed with integer-nanosecond math, so it never accumulates floating-point drift. Wall-clock `startTime` / `endTime` stamps come from `Date.now()`.\n\n## Installation\n\n```sh\nnpm install perfy\n```\n\n## Usage\n\nCall `perfy.start('name')` to create a timer and mark its start, then `perfy.end('name')` to get the elapsed-time [result](#the-result-object). By default the instance is destroyed once ended.\n\n```ts\nimport { perfy } from 'perfy';\n\nperfy.start('loop-stuff');\n// ...some heavy stuff here...\nconst result = perfy.end('loop-stuff');\nconsole.log(result.time); // -> 1.459 (sec.)\n```\n\n...or wrap the work in `exec()` and let Perfy time it for you:\n\n```ts\nperfy.exec('async-stuff', (done) => {\n // ...some heavy async stuff here...\n const result = done();\n console.log(result.time); // -> 1.459 (sec.)\n});\n```\n\nThe exported `perfy` is a shared singleton — the simplest way to use the library. When you want an **isolated registry** (or a custom clock, e.g. in tests), construct your own:\n\n```ts\nimport { Perfy } from 'perfy';\n\nconst perfy = new Perfy();\n```\n\n## Exports\n\nEverything is a **named** export (there is no default export):\n\n```ts\nimport {\n perfy, // shared Perfy singleton — the simplest entry point\n Perfy, // class — construct an isolated registry: new Perfy(clock?)\n PerfyItem, // a single timing instance (advanced / typing)\n PerfyError, // Error subclass thrown on failure, with a `.code`\n createNanoClock, // build a NanoClock from given host objects\n defaultNanoClock // the NanoClock selected for this environment\n} from 'perfy';\n\nimport type {\n IPerfyResult, // the elapsed-time result object\n IPerfyMeasurement, // the disposable handle returned by measure()\n NanoClock, // () => bigint monotonic nanosecond clock\n PerfyErrorCode, // 'NAME_REQUIRED' | 'NO_INSTANCE' | 'NOT_STARTED' | 'INVALID_CALLBACK' | 'NO_CLOCK'\n DoneFn, // the `done` callback passed to a callback-style exec task\n SyncTask,\n AsyncTask,\n PromiseTask,\n PerfyTask // SyncTask | AsyncTask | PromiseTask\n} from 'perfy';\n```\n\n## API\n\nEvery method that takes a `name` throws a [`PerfyError`](#errors) with code `NAME_REQUIRED` when it is empty.\n\n| Method | Returns | Description |\n| ------ | ------- | ----------- |\n| `start(name, autoDestroy?)` | `Perfy` | Creates a new instance under `name` and marks its start time. Reusing a name overwrites it. `autoDestroy` (default `true`) drops the instance when `end()` is called. Chainable. |\n| `end(name)` | [`IPerfyResult`](#the-result-object) | Ends the instance and returns the elapsed-time result. If `autoDestroy` was left on, the instance is removed right after. Calling `end()` again on a kept instance returns the same cached result. Throws `NO_INSTANCE` if no such instance exists. |\n| `lap(name)` | [`IPerfyResult`](#the-result-object) | Records a **split** — the elapsed time since the previous lap (or since `start` for the first) — then advances the lap marker. The instance keeps running; `end()` still reports the total from `start`. Throws `NO_INSTANCE` if no such instance exists. |\n| `measure(name, onEnd?)` | [`IPerfyMeasurement`](#the-result-object) | Starts a kept instance and returns a **disposable** whose `[Symbol.dispose]` ends it — so a `using` declaration times its enclosing scope. The result stays retrievable via `result(name)`; pass `onEnd` to receive it immediately. Disposing twice is a no-op. |\n| `exec([name,] fn)` | [`IPerfyResult`](#the-result-object) \\| `Promise` \\| `Perfy` | Times the execution of `fn`, picking the mode from the task itself. **Synchronous** (`fn` returns a non-thenable) → ended automatically, result returned. **Promise-returning** (`fn` returns a promise) → awaited, resolves to the result (a rejection is propagated). **Callback-style** (`fn(done)` declares a `done` argument) → must call `done()` to end; returns the `Perfy` instance immediately. Pass a `name` to keep the instance. Throws `INVALID_CALLBACK` if `fn` is not a function. |\n| `result(name)` | [`IPerfyResult`](#the-result-object) \\| `null` | The stored result of a kept, ended instance — or `null` if it does not exist or has not ended yet. |\n| `exists(name)` | `boolean` | Whether an instance currently exists under `name`. `false` once an auto-destroyed instance has ended. |\n| `names()` | `string[]` | Names of all existing instances. |\n| `count()` | `number` | Number of existing instances. |\n| `destroy(name)` | `Perfy` | Destroys the instance under `name`, if any. Chainable. |\n| `destroyAll()` | `Perfy` | Destroys all existing instances. Chainable. |\n\n### The Result Object\n\n`end()` (and `exec()` / `result()`) return an `IPerfyResult` — every field is a plain `number`/`string`, so the object is safe to `JSON.stringify`.\n\n| Property | Type | Description |\n| -------- | ---- | ----------- |\n| `name` | `string` | Name of the instance (`''` for an unnamed `exec()`). |\n| `time` | `number` | Full elapsed time in **seconds** (float, 3 decimals). e.g. `1.235` |\n| `milliseconds` | `number` | Full elapsed time in **milliseconds** (float). e.g. `1235.125` |\n| `nanoseconds` | `number` | Full elapsed time in **nanoseconds**. e.g. `1235125283` |\n| `summary` | `string` | Human-readable shorthand. e.g. `'loop: 1.235 sec.'` |\n| `startTime` | `number` | UTC wall-clock time (ms) at start, via `Date.now()`. e.g. `1533302465251` |\n| `endTime` | `number` | UTC wall-clock time (ms) at end, via `Date.now()`. e.g. `1533302466486` |\n\n## Examples\n\n**Reading the elapsed time in different units:**\n\n```ts\nperfy.start('metric');\n// ...\nconst r = perfy.end('metric');\nconsole.log(`${r.time} sec.`); // -> 1.234 sec.\nconsole.log(`${r.milliseconds} ms.`); // -> 1234.567 ms.\nconsole.log(r.summary); // -> metric: 1.234 sec.\n```\n\n**Auto-destroy (default):**\n\n```ts\nperfy.start('metric').count(); // -> 1\nperfy.end('metric');\nperfy.count(); // -> 0 (destroyed on end)\n```\n\n**Keep the instance (disable `autoDestroy`):**\n\n```ts\nperfy.start('metric', false);\nperfy.end('metric').time; // -> 0.123\nperfy.exists('metric'); // -> true (kept)\nperfy.result('metric'); // -> the same result object\n```\n\n**Timing a synchronous function** — `exec()` returns the result directly:\n\n```ts\nconst result = perfy.exec(() => {\n // sync work\n});\nconsole.log(result.time);\n```\n\n**Timing a promise / `async` function** — `exec` awaits it and resolves to the result:\n\n```ts\nconst result = await perfy.exec('fetch', async () => {\n await fetch('https://example.com');\n});\nconsole.log(result.time);\n```\n\n**Timing a callback-style async function** — call `done()` when finished:\n\n```ts\nperfy.exec((done) => {\n setTimeout(() => {\n const result = done();\n console.log(result.time);\n }, 1000);\n});\n```\n\n**Laps** — record splits within one running timer:\n\n```ts\nperfy.start('pipeline');\nloadData();\nconsole.log('load:', perfy.lap('pipeline').time);\ntransform();\nconsole.log('transform:', perfy.lap('pipeline').time);\nconsole.log('total:', perfy.end('pipeline').time);\n```\n\n**Scope timing with `using`** — the timer ends automatically when the block exits:\n\n```ts\n{\n using _ = perfy.measure('block', (r) => console.log(r.time));\n // ...work...\n} // ended here\n```\n\n**Named `exec()`** keeps the instance for later retrieval:\n\n```ts\nperfy.exec('async-op', (done) => {\n done();\n});\nperfy.exists('async-op'); // -> true\nperfy.result('async-op'); // -> the result object\n```\n\n**Destroy everything:**\n\n```ts\nperfy.destroyAll().count(); // -> 0\n```\n\n### Errors\n\nEvery failure throws a `PerfyError` — an `Error` subclass carrying a stable, machine-readable `code` (`NAME_REQUIRED`, `NO_INSTANCE`, `NOT_STARTED`, `INVALID_CALLBACK`, `NO_CLOCK`):\n\n```ts\nimport { perfy, PerfyError } from 'perfy';\n\ntry {\n perfy.end('never-started');\n} catch (err) {\n if (err instanceof PerfyError && err.code === 'NO_INSTANCE') {\n // handle it\n }\n}\n```\n\n## Tests & Quality\n\n100% test coverage (statements, branches, functions, lines) and a **100% [Stryker](https://stryker-mutator.io) mutation score**, run across Node.js 22 & 24 in CI.\n\n## Changelog\n\nSee [**CHANGELOG.md**](CHANGELOG.md). **v2 is a breaking release** (ESM-only, universal clock, streamlined result object) — the migration notes live there.\n\n## Related\n\n- [**tasktimer**](https://github.com/onury/tasktimer) — An accurate timer utility for running periodic tasks on the given interval ticks or dates.\n\n## License\n\n© 2026, Onur Yıldırım. [**MIT**](LICENSE) License.\n","readmeFilename":"README.md","users":{"emjimadhu":true,"flumpus-dev":true}}