lighthouse.audit.js

// Import the required npm packages
const fs = require('fs')
const lighthouse = require('lighthouse')
const chromeLauncher = require('chrome-launcher')

// Read the csv file and store the
// urls in an array
const array = fs.readFileSync('site_urls.csv').toString().split('\n')

// Declare a resultant array to store
// the generated scores and initialize
// it with headings
const result = []
result.push(
  ', URL, Mobile_Performance, Mobile_Accessibility, Mobile_Best_Practices, Mobile_SEO, Desktop_Performance, Desktop_Accessibility, Desktop_Best_Practices, Desktop_SEO'
);

// The async await is used to ensure
// non-blocking code execution
(async () => {
  const chrome = await chromeLauncher
    .launch({ chromeFlags: ['--headless'] })

  // Declaring an object to specify score
  // for what audits, categories and type
  // of output that needs to be generated
  const options = {
    logLevel: 'info',
    output: 'csv',
    onlyCategories: [
      'performance',
	    'accessibility',
      'best-practices',
      'seo'
    ],
    audits: [
	  'first-meaningful-paint',
	  'first-cpu-idle',
	  'byte-efficiency/uses-optimized-images',
      'speed-index',
      'interactive'
    ],
    port: chrome.port,
  }

  // Traversing through each URL
  for (i in array) {
    // Separate strategy for Mobile
    // and Desktop view
    for (let x = 0; x < 2; x++) {
      const configuration = ''

      if (x == 0) options.strategy = 'mobile'
      else options.strategy = 'desktop'

      const runnerResult =
      await lighthouse(array[i], options)

      // Current report
      const reportCsv = runnerResult.report

      // URL to be put only for first iteration
      // (mobile and not separately for desktop)
      if (x == 0) {
        result.push('\n')
        result.push(runnerResult.lhr.finalUrl)
      }

      // If score can't be determined, NA is
      // put in the corresponding field.
      if (runnerResult.lhr.categories.performance.score) {
        result.push(runnerResult.lhr
          .categories.performance.score * 100)
      }
      else {
        result.push('NA')
      }

      if (runnerResult.lhr.categories.accessibility.score) {
        result.push(runnerResult.lhr
          .categories.accessibility.score * 100)
      }
      else {
        result.push('NA')
      }

      if (runnerResult.lhr.categories['best-practices'].score) {
        result.push(runnerResult.lhr
          .categories['best-practices'].score * 100)
      }
      else {
        result.push('NA')
      }

      if (runnerResult.lhr.categories.seo.score) {
        result.push(runnerResult.lhr
          .categories.seo.score * 100)
      }
      else {
        result.push('NA')
      }
    }
  }

  // Append the result in a report.csv
  // file and end the program
  fs.appendFileSync('lhreport.csv', result.toString())
  await chrome.kill()
})()