How to use lighthouse CLI to optimize website speed

  1. Home
  2. Blog
Louis•4 mins read
Lighthouse#dev

In today's fast-paced digital world, website speed is crucial for user experience and SEO. One of the most powerful tools for analyzing and improving website performance is Google's Lighthouse. While many are familiar with its browser extension, the Lighthouse CLI offers more flexibility and can be integrated into your development workflow. This guide will walk you through the steps to use Lighthouse CLI to optimize your website speed effectively.

What is Lighthouse CLI?

Lighthouse is an open-source, automated tool for improving the quality of web pages. It provides audits for performance, accessibility, SEO, and more. The CLI version allows you to run these audits directly from the command line, making it easier to integrate into build processes and continuous integration systems.

Installing Lighthouse CLI

To get started with Lighthouse CLI, you need to have Node.js installed on your machine. If you haven't already installed Node.js, you can download it from nodejs.org.

Once Node.js is installed, you can install Lighthouse CLI globally using npm (Node Package Manager):

npm install -g lighthouse

Running Lighthouse CLI

With Lighthouse CLI installed, you can run it on any website. The basic command is straightforward:

lighthouse <url>

For example, to run Lighthouse on https://example.com, you would use:

lighthouse https://example.com

This command will generate a report in HTML format and open it in your default browser.

Customizing Lighthouse CLI Runs

Lighthouse CLI offers several options to customize your audits. Here are some useful flags:

  • --output: Specify the output format (html, json, or csv).
  • --output-path: Define the file path to save the report.
  • --only-categories: Run specific audits (e.g., performance, accessibility, best-practices, SEO, PWA).

For example, to run an audit focused only on performance and save the report as a JSON file, you would use:

lighthouse https://example.com --only-categories=performance --output=json --output-path=./report.json

Integrating Lighthouse CLI into Your Workflow

To make the most of Lighthouse CLI, consider integrating it into your development workflow. Here are a few ways to do this:

Using npm Scripts

You can add Lighthouse commands to your project's package.json file under the scripts section. This allows you to run audits with a simple command.

"scripts": {
  "audit": "lighthouse https://example.com --only-categories=performance --output=json --output-path=./report.json"
}

Now, you can run the audit using:

npm run audit

Continuous Integration

Integrate Lighthouse CLI into your CI/CD pipeline to ensure your site maintains high performance standards. Here’s an example using GitHub Actions:

name: Lighthouse CI

on: [push]

jobs:
  lighthouse:
    runs-on: ubuntu-latest
    steps:
    - name: Checkout code
      uses: actions/checkout@v2

    - name: Install Node.js
      uses: actions/setup-node@v2
      with:
        node-version: '14'

    - name: Install Lighthouse CLI
      run: npm install -g lighthouse

    - name: Run Lighthouse
      run: lighthouse https://example.com --output=json --output-path=./report.json

Analyzing Lighthouse Reports

The Lighthouse report provides a wealth of information. Key sections include:

  • Performance: Metrics like First Contentful Paint (FCP), Speed Index, and Time to Interactive (TTI).
  • Accessibility: Checks for common accessibility issues.
  • Best Practices: Ensures your site follows web standards and best practices.
  • SEO: Basic SEO checks.

Focus on the performance section for speed optimization. Look for areas where your site is lagging and follow the recommendations provided.

Conclusion

Using Lighthouse CLI is a powerful way to audit and optimize your website's performance. By integrating it into your development workflow, you can continuously monitor and improve your site, ensuring a fast and smooth experience for your users. Start using Lighthouse CLI today to take your website speed to the next level!

For more tips and tricks on website speed optimization, be sure to check out our other blog posts at speed.Larger.io/blog.

© 2024