marky

JavaScript timer based on performance.mark() and performance.measure(), providing high-resolution timings as well as nice Dev Tools visualizations.

For browsers that don't support performance.mark(), it falls back to performance.now() or Date.now(). In Node, it uses process.hrtime().

Quick start

Install via npm:

npm install marky

Or as a script tag:

<script src="https://unpkg.com/marky/dist/marky.min.js"></script>

Then take some measurements:

var marky = require('marky');

marky.mark('expensive operation');
doExpensiveOperation();
marky.stop('expensive operation');

Why?

The User Timing API is more performant than console.time() and console.timeEnd(), and more accurate than Date.now(). Also, you get nice visualizations in Chrome Dev Tools:

As well as Edge F12 Tools:

This is because marky adds standard PerformanceEntries to the Performance Timeline. In principle other browsers and analytics providers can use the same data.

API

marky.mark() begins recording, and marky.stop() finishes recording:

marky.mark('releaseTheHounds');
releaseTheHounds();
marky.stop('releaseTheHounds');

You can also do more complex scenarios:

function setSail() {
  marky.mark('setSail');
  marky.mark('raiseTheAnchor');
  raiseTheAnchor();
  marky.stop('raiseTheAnchor');
  marky.mark('unfurlTheSails');
  unfurlTheSails();
  marky.stop('unfurlTheSails');
  marky.stop('setSail');
}

marky.stop() also returns a PerformanceEntry:

marky.mark('manTheTorpedos');
manTheTorpedos();
var entry = marky.stop('manTheTorpedos');

The entry will look something like:

{
  "entryType": "measure",
  "startTime": 1974112,
  "duration": 350,
  "name": "manTheTorpedos"
}

You can get all entries using:

var entries = marky.getEntries();

This provides a list of all measures ordered by startTime, e.g.:

[
  {
    "entryType": "measure",
    "startTime": 1974112,
    "duration": 350,
    "name": "numberOne"
  },
  {
    "entryType": "measure",
    "startTime": 1975108,
    "duration": 300,
    "name": "numberTwo"
  },
  {
    "entryType": "measure",
    "startTime": 1976127,
    "duration": 250,
    "name": "numberThree"
  }
]

Browser support

marky is tested in the following browsers/environments:

• IE 9+
• Safari 8+
• iOS 8+
• Android 4.4+
• Chrome
• Firefox
• Edge
• Node 4+

Per the spec, browsers only need to hold a minimum of 150 entries in their Performance Timeline buffer. Notably Firefox throttles their buffer to 150, which for marky means you can get a maximum of 50 entries from marky.getEntries() (because marky creates two marks and a measure).

If you need to get more than 50 entries from marky.getEntries(), you can do:

if (typeof performance !== 'undefined' && performance.setResourceTimingBufferSize) {
  performance.setResourceTimingBufferSize(10000); // or however many you need
}

In Node and browsers that don't support the User Timing API, marky follows the behavior of Edge and Chrome, and does not limit the number of entries. marky.stop() and marky.getEntries() will return pseudo-PerformanceEntry objects.

Credits

Thanks to @toddreifsteck for feedback on this project and clarifications on the User Timing API.