Estimo is a tool for measuring parse / compile / execution time of javascript.

This tool can emulate CPU throttling, Network conditions, use Chrome Device emulation and more for measuring javascript performance.

Inspired by Size Limit. Thanks @ai and @aslushnikov for support.

JavaScript is the most expensive part of our frontend.

3.5 seconds to process 170 KB of JS and 0.1 second for 170 KB of JPEG.

JS API

const path = require('path')
const estimo = require('estimo')

;(async () => {
  const report = await estimo(path.join(__dirname, 'examples', 'example.js'))
  console.log(report)
})()

CLI

estimo -r ./examples/example.js

Output

;[
  {
    name: 'example.js',
    parseHTML: 1.01,
    styleLayout: 34.08,
    paintCompositeRender: 1.4,
    scriptParseCompile: 1.04,
    scriptEvaluation: 8.11,
    javaScript: 9.15,
    garbageCollection: 0,
    other: 8.2,
    total: 53.84
  }
]

• name - Resource name (file name or web url).

• parseHTML - Time which was spent for ParseHTML, ParseAuthorStyleSheet events.

• styleLayout - Time which was spent for ScheduleStyleRecalculation, UpdateLayoutTree, InvalidateLayout, Layout events.

• paintCompositeRender - Time which was spent for Animation, HitTest, PaintSetup, Paint, PaintImage, RasterTask, ScrollLayer, UpdateLayer, UpdateLayerTree, CompositeLayers events.

• scriptParseCompile - Time which was spent for v8.compile, v8.compileModule, v8.parseOnBackground events.

• scriptEvaluation - Time which was spent for EventDispatch, EvaluateScript, v8.evaluateModule, FunctionCall, TimerFire, FireIdleCallback, FireAnimationFrame, RunMicrotasks, V8.Execute events.

• javaScript - Time which was spent for both event groups (scriptParseCompile and scriptEvaluation).

• garbageCollection - Time which was spent for MinorGC, MajorGC, BlinkGC.AtomicPhase, ThreadState::performIdleLazySweep, ThreadState::completeSweep, BlinkGCMarking events.

• other - Time which was spent for MessageLoop::RunTask, TaskQueueManager::ProcessTaskFromWorkQueue, ThreadControllerImpl::DoWork events.

• total - Total time.

All metrics are in milliseconds.

We measure system-cpu time. The number of seconds that the process has spent on the CPU.

We not including time spent waiting for its turn on the CPU.

All results measured in time. It means that results could be unstable depends on available on your device resources.

You can use runs option to run estimo N times and get median value as a result.

JS API

const report = await estimo(['/path/to/examples/example.js'], { runs: 10 })

CLI

estimo -r /path/to/examples/example.js -runs 10

You can compare metrics of an origin file with others its versions to understand consequences on performance.

We take the first file as a baseline. All rest files will be compared with the baseline.

JS API

const report = await estimo(['lib-1.0.5.js', 'lib-1.1.0.js'], { diff: true })

CLI

estimo -r lib-1.0.5.js lib-1.1.0.js -diff

Output

;[
  {
    name: 'lib-1.0.5.js',
    parseHTML: 1.48,
    styleLayout: 44.61,
    paintCompositeRender: 2.19,
    scriptParseCompile: 1.21,
    scriptEvaluation: 9.63,
    javaScript: 10.84,
    garbageCollection: 0,
    other: 9.95,
    total: 69.06
  },
  {
    name: 'lib-1.1.0.js',
    parseHTML: 2.97,
    styleLayout: 61.02,
    paintCompositeRender: 2.11,
    scriptParseCompile: 2.11,
    scriptEvaluation: 19.28,
    javaScript: 21.39,
    garbageCollection: 0,
    other: 15.49,
    total: 102.98,
    diff: {
      parseHTML: '2.97 (+50.17% 🔺)',
      styleLayout: '61.02 (+26.9% 🔺)',
      paintCompositeRender: '2.11 (-3.8% 🔽)',
      scriptParseCompile: '2.11 (+42.66% 🔺)',
      scriptEvaluation: '19.28 (+50.06% 🔺)',
      javaScript: '21.39 (+49.33% 🔺)',
      garbageCollection: '0 (N/A)',
      other: '15.49 (+35.77% 🔺)',
      total: '102.98 (+32.94% 🔺)'
    }
  }
]

The CPU Throttling Rate Emulation allows you to simulate CPU performance.

• cpuThrottlingRate (default: 1) - Sets the CPU throttling rate. The number represents the slowdown factor (e.g., 2 is a "2x" slowdown).

JS API:

await estimo('/path/to/example.js', { cpuThrottlingRate: 4 })

CLI:

estimo -r ./examples/example.js -cpu 4

The Network Emulation allows you to simulate a specified network conditions.

• emulateNetworkConditions (default: undefined) - One of puppeteer network conditions descriptor.

JS API:

await estimo('/path/to/example.js', { emulateNetworkConditions: 'Slow 3G' })

CLI:

estimo -r ./examples/example.js -net Slow\ 3G

The Chrome Device Emulation allow you to simulate a specified device conditions.

• device (default: undefined) - One of puppeteer devices descriptor.

JS API

const report = await estimo('/path/to/example.js', { device: 'Galaxy S5' })

CLI

estimo -r ./examples/examples.js -device Galaxy\ S5

When using CLI, for device names with spaces you should use symbols escaping.

You can specify how long estimo should wait for page to load.

• timeout (default: 20000) - Sets timeout in ms.

JS API:

await estimo('/path/to/example.js', { timeout: 90000 })

CLI:

estimo -r ./examples/example.js -timeout 90000

JS API

const report = await estimo([
  '/path/to/libs/example.js',
  '/path/to/another/example/lib.js'
])

CLI

estimo -r /path/to/example.js https://unpkg.com/react@16/umd/react.development.js

You can use all features not only with js files, but with web pages too.

We will wait for navigation to be finished when the load event is fired.

JS API

const report = await estimo('https://www.google.com/')

CLI

estimo -r https://www.google.com/

npm i estimo

or

yarn add estimo

It uses puppeteer to generate Chrome Timelines. Which can be transformed in human-readable shape by Tracium.

We will use your local Chrome if it suitable for using with Estimo.

Keep in mind there result depends on your device and available resources.

• Size Limit

Pull requests, feature ideas and bug reports are very welcome. We highly appreciate any feedback.