Posted by Rutuja Konde

In the current world of development, the performance of the website is a critical aspect. A fast, user-friendly, optimized website not only invite more visitors to your site but also keep them engaged. Lighthouse is an open-source tool created by Google that has become an essential part of the tools available to web developers and digital marketers striving for higher website performance. In this blog, we will learn what Lighthouse is, how it works and how it is an essential tool for web optimization. 

What Is Google Lighthouse?

Google Lighthouse is an open-source tool that automatically checks web page’s quality based on the set of parameters and offers the appropriate recommendations. The tool assesses websites based on the following five broad categories: 

1. Performance: Lighthouse checks how fast your webpage loads and becomes interactive. It measures when content appears, when the page is fully loaded, and when it’s ready for user input, helping developers make faster, more user-friendly websites. 
2. Accessibility: Lighthouse checks if your site is accessible to people with disabilities by evaluating things like colour contrast, keyboard navigation, and image alt text. It also looks at form layout and overall HTML to ensure it’s easy for everyone to use, leading to better websites for all. 
3. Best Practices: Lighthouse’s Best Practices ensure your website is safe, up-to-date, and secure. It checks for HTTPS, updated code, and safe libraries, as well as proper permissions and compatibility across devices and browsers, leading to a faster and safer user experience. 
4. SEO: SEO checks in Lighthouse help improve your site’s visibility on search engines. It ensures your page is accessible to search engines, uses proper headings, has a good title and description, and is mobile-friendly. Following these tips can boost your site’s ranking and attract more organic traffic. 
5. Progressive Web App (PWA): PWA tests make your website behave like an app by ensuring it’s fast, reliable, and engaging. It checks offline functionality, fast loading, HTTPS security, installability, and responsiveness across devices. Following these standards helps provide a smooth app-like experience for users. 
    

How Does Google Lighthouse Work?

Lighthouse can perform audits by approximating a user experience on your website. Here’s how it works: 

• Initiating the Audit: Users can use Lighthouse through Google Chrome DevTools, the command line or Node.js. To start the audit, just open your website and then wait when the Lighthouse will analyse the page. 
   
  Example Script: Using Node.js Script

const lighthouse = require('lighthouse'); 
const chromeLauncher = require('chrome-launcher'); 
  
(async () => { 
    const chrome = await chromeLauncher.launch({ chromeFlags: ['--headless'] }); 
  
    const options = { logLevel: 'info', output: 'html', onlyCategories: ['performance'], port: chrome.port }; 
  
    const runnerResult = await lighthouse('https://example.com', options); 
  
    // Use results 
    console.log('Report is done:', runnerResult.lhr.finalUrl); 
    console.log('Performance score is', runnerResult.lhr.categories.performance.score * 100); 
  
    await chrome.kill(); 
})();

The script runs Lighthouse on the specified URL and generates performance scores and an HTML report. 

• Simulating User Conditions: Lighthouse simulates how an average user might experience your website. For example, by testing it on a mid-range Android phone with a 4G internet connection. This helps you understand how your site performs under typical conditions, especially for users with slower internet speeds or less powerful devices 
  Example: Using Command Line 

lighthouse https://example.com --throttling.cpuSlowdownMultiplier=4 --throttling-method=simulate --output html --view

C:\Users\user>lighthouse https://www.neovasolutions.com/ --throttling.cpuSlowdownMultiplier=4 --throttling-method=simulate --output html --view We're constantly trying to improve Lighthouse and its reliability. 
Learn more: https://github.com/GoogleChrome/Lighthouse/blob/main/docs/error-reporting.md 
May we anonymously report runtime exceptions to improve the tool over time? 
We'll remember your choice, but you can also use the flag --[no-]enable-error-reporting (y/N) · false 
LH:ChromeLauncher Waiting for browser... +0ms 
LH:ChromeLauncher Waiting for browser... +1ms 
LH:ChromeLauncher Waiting for browser... +509ms 
LH:ChromeLauncher Waiting for browser... +521ms 
LH:ChromeLauncher Waiting for browser... +18ms 
LH:status Connecting to browser +15 
LH:status Navigating to about:blank +7ms 
LH:status Benchmarking machine +78ms 
LH:status Preparing target for navigation mode +1s 
LH:status Cleaning origin data +133ms 
LH:status Cleaning browser cache +1s 
LH:status Preparing network conditions +2s 
LH:status Navigating to https://www.neovasolutions.com/ +822ms

• Generating Reports on Google Lighthouse: After the audit, Lighthouse prepares few pages, and at the end of each page there will be a concise conclusion about how your site navigates and where it fails. It has advantages and disadvantages for your website and provides tips. Example Report:

Why Should You Use Lighthouse for Web Optimization?

1. Improves Core Web Vitals

Core Web Vitals focus on making websites fast, easy to use, and stable while loading. Lighthouse measures these factors and gives helpful suggestions to improve them. Fixing these issues makes your site work better for visitors and can improve your Google ranking too.

2. Boosts User Experience

Performance affects the user satisfaction on the website. Long time-to-locate, and minimal visibility makes users turn away from such sites. It is a web app that detects areas of high-performance cost and accessibility problems so you can deliver a frictionless experience.

3. Enhances SEO

It will also reveal that search engines favour well optimized web sites. Lighthouse reviews a site’s metadata, responsiveness, and other SEO factors. It also offers tips to improve its search rankings.

4. Ensures Modern Standards

The web development continues to grow fast and remain standards-conscious to make it secure and compatible. Lighthouse looks for old technologies, insecure links, and low-quality coding patterns, so you will know when it’s time to improve.

5. Supports Progressive Web App (PWA) Development

We guarantee that if you are going to create a PWA, none is as useful as Lighthouse. It helps ensure that key requirements like offline mode, fast loading, and mobile-first design are properly implemented in your app.

How to Access Google Lighthouse

1. Using Chrome DevTools:

• Open the website in Chrome, right-click, select “Inspect,” go to the Lighthouse tab, and click “Generate report.”

2. Command Line Interface:

• Install Lighthouse via npm (npm install -g lighthouse).

C:\Users\user>npm install -g lighthouse 
added 164 packages in 2m 
11 packages are looking for funding 
run `npm fund` for details

• Run audits directly from your terminal.

C:\Users\user>lighthouse https://www.neovasolutions.com/ --throttling.cpuSlowdownMultiplier=4 --throttling-method=simulate --output html --view 
We're constantly trying to improve Lighthouse and its reliability. 
Learn more: https://github.com/GoogleChrome/Lighthouse/blob/main/docs/error-reporting.md 
May we anonymously report runtime exceptions to improve the tool over time? 
We'll remember your choice, but you can also use the flag --[no-]enable-error-reporting (y/N) · false 
LH:ChromeLauncher Waiting for browser... +0ms 
LH:ChromeLauncher Waiting for browser... +1ms 
LH:ChromeLauncher Waiting for browser... +509ms 
LH:ChromeLauncher Waiting for browser... +521ms 
LH:ChromeLauncher Waiting for browser... +18ms 
LH:status Connecting to browser +15 
LH:status Navigating to about:blank +7ms 
LH:status Benchmarking machine +78ms 
LH:status Preparing target for navigation mode +1s 
LH:status Cleaning origin data +133ms 
LH:status Cleaning browser cache +1s 
LH:status Preparing network conditions +2s 
LH:status Navigating to https://www.neovasolutions.com/ +822ms 
LH:status Getting artifact: DevtoolsLog +19s 
LH:status Getting artifact: Trace +0ms 
LH:status Getting artifact: RootCauses +1ms 
LH:status Getting artifact: Accessibility +1s 
LH:status Getting artifact: AnchorElements +1ms

By default, Lighthouse generates an HTML report in the current working directory.

3. Google Lighthouse CI:

1. Set it up by installing the Lighthouse CI CLI and configuring it in your CI workflow to run audits and generate reports.
2. Check Results Lighthouse CI gives you reports with performance scores and highlights issues to fix.

In this example, the action kicked in and failed, since I have a large image on the about page.

Conclusion

Google Lighthouse is a valuable tool that helps improve your website in many ways. It checks your site’s speed, accessibility, and best practices, providing clear feedback on areas for improvement. Regular use helps keep your site fast, user-friendly, and up to date with modern web standards, ultimately contributing to a better web experience.