@s-ui/react-web-vitals

Track the performance of pages using Core Web Vitals in real-time for all the visits

Installation

npm install @s-ui/react-web-vitals

Setup

Wrap your app component with the exported one

import WebVitalsReporter from '@s-ui/react-web-vitals'

export default function App() {
  return (
    <WebVitalsReporter>
      <main />
    </WebVitalsReporter>
  )
}

In order to work properly the App component should be wrapped by SUI Context and SUI Router providers

import withAllContexts from '@s-ui/hoc/lib/withAllContexts'
import {Router} from '@s-ui/react-router'

const context = {}
const Root = withAllContexts(context)(Router)

ReactDOM.render(<Root />, document.getElementById('root'))

Logging

Logger

By default the metrics will be sent using the timing method of the logger. The logger should be provided by the SUI Context.

import withAllContexts from '@s-ui/hoc/lib/withAllContexts'
import {Router} from '@s-ui/react-router'

const logger = new Logger() // your custom logger
const context = {logger}
const Root = withAllContexts(context)(Router)

ReactDOM.render(<Root />, document.getElementById('root'))

The distribution method from the logger will be called with an object that follows the next schema

{
  "name": "cwv",
  "amount": 10,
  "tags": [
    {
      "key": "name",
      "value": "CLS"
    }
    {
      "key": "pathname",
      "value": "/products/:id"
    },
    {
      "key": "type",
      "value": "desktop"
    }
  ]
}

Custom

If onReport callback prop is set instead of reporting the metrics to the logger the callback will be used.

import WebVitalsReporter from '@s-ui/react-web-vitals'

export default function App() {
  const handleReport = metric => {
    console.log(metric) // do something
  }

  return (
    <WebVitalsReporter onReport={handleReport}>
      <main />
    </WebVitalsReporter>
  )
}

The callback will be called with an object that follows the next schema

{
  "name": "LCP",
  "amount": 10,
  "pathname": "/products/:id",
  "type": "desktop"
}

Metrics

Use metrics prop to set the core web vitals that you want to track. Choose between: TTFB, LCP, FID, CLS and INP. If not set all core web vitals will be tracked

import WebVitalsReporter from '@s-ui/react-web-vitals'

export default function App() {
  return (
    <WebVitalsReporter metrics={['LCP', 'CLS']}>
      <main />
    </WebVitalsReporter>
  )
}

New LCP Subpart Metrics

The system now tracks and logs the following LCP subpart metrics as recommended by web.dev:

Metric	Code	Description
Time to First Byte	LCP_TTFB	Time until the browser receives the first byte of HTML
Resource Load Delay	LCP_RLDE	Time between first HTML byte and start of LCP resource loading
Resource Load Duration	LCP_RLDU	Time taken to load the LCP resource
Element Render Delay	LCP_ERDE	Time from resource load completion to actual rendering

Each of these metrics is automatically distributed through the logger system with appropriate tags, allowing for detailed performance analysis and targeted optimization efforts.

Benefits

This granular approach to LCP tracking enables:

• More precise identification of loading bottlenecks
• Better targeted optimization strategies
• Improved Core Web Vitals scores
• Clearer correlation between performance issues and specific page elements

Device type

Use deviceType prop to set the device type that will be send when a metric is reported. Choose between: desktop, tablet and mobile. If not set the browser property from the SUI Context will be used

import WebVitalsReporter from '@s-ui/react-web-vitals'

export default function App() {
  return (
    <WebVitalsReporter deviceType="desktop">
      <main />
    </WebVitalsReporter>
  )
}

Allowed routes

Use allowed prop if you only want to track a set of pathnames or route ids

import WebVitalsReporter from '@s-ui/react-web-vitals'

export default function App() {
  return (
    <WebVitalsReporter allowed={['/products/:id', 'search']}>
      <main />
    </WebVitalsReporter>
  )
}