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How Lighthouse for Web Performance Testing Helps Improve E-Commerce Web and Mobile Solutions

It takes you about two seconds to read this title.

1-2 seconds is the optimal web page load time. If it takes longer, customers are likely to leave your e-commerce website.

Shoppers hate waiting. According to Kissmetrics, 79% of customers are less likely to buy from a website again if a website performance is poor. A 2-second delay may result in an 87% abandonment rate. Besides, slow loading may affect your website ranking by search engines.

You can't do without website performance testing if you wish to improve the value and conversion of a current e-commerce site. Read this article and learn about the Lighthouse performance testing tool and key testing metrics used to improve website performance.
By Kristina Kudryavtseva, Test Automation Engineer at Solvd
August 18, 2021
How to Use Lighthouse for Performance Testing?
Lighthouse is an open-source, automated tool that QA engineers use to estimate the quality of web pages. This tool provides excellent functionality for web performance testing:

  • Since the tool is open-source, it is almost free of charge.

  • Its flexibility allows QA engineers to simulate network throttling, make device emulation, and create other specific audit conditions that may impact performance metrics.

  • It can be complemented by Puppeteer. This Node.js library enables creating a test flow necessary to test some types of target pages (like a web page behind authentication).

  • Lighthouse reports involve metrics that Google uses for ranking.

  • Engineers may configure the final report by excluding some categories and including specific audits.

  • Test engineers may go beyond default Lighthouse audits and create custom ones.

When it comes to e-commerce website performance testing, estimating just a home page is not enough to get a 360-degree view of the web solution performance. Lighthouse performance audit involves checking the Home page, Account page, Product listing page, Product detail page, Cart, Checkout, and Order confirmation page, as a minimum.

QA engineers may make a complex audit of web pages by assessing the quality in five categories:

1. Performance.
The tool measures how quickly a website or app loads and how quickly users can access or view the content.

2. Accessibility. Test engineers may use the tools to check a web page for common accessibility errors, may find room for improvement, and suggest additional tech stacks.

3. Best practices.
This audit category describes the security aspects of a website and modern standards of web development.

4. Search engine optimization (SEO).
This category shows how well search engines rank a website or app and display it in the search results.

5. Progressive web applications.
PWA is needed to deliver enhanced app capabilities, reliability, and installability based on a single codebase. It permits reaching out to anyone, anywhere, and on any device, offering users to jump from a web page to download a separate app.

For each category, you receive reference documentation, clarifications on why you do need this type of audit, and what improvements you can make.

Such an inclusive QA approach using Lighthouse web performance testing ensures an excellent overview of the quality of your site as a whole. It checks the performance of your site equally well on desktop, mobile, and web applications.
Performance Testing of E-commerce Applications Using Lighthouse
Let's take the Lighthouse performance testing category as an observation point. It involves key metrics that you should take into account to promote your web solution. This way, you can improve such business KPIs as conversion, churn rate, purchase, and customer loyalty.

A QA team will use Lighthouse to provide you with an in-depth overview of your site performance. The tool allows generating insightful reports and uses 6 metrics to assess website performance:

  • LCP (Largest Contentful Paint). This metric lets engineers measure how long it takes your website to load and show the largest content.

  • TBT (Total Blocking Time) measures the total amount of time when a page doesn't respond to mouse clicks, screen taps, or keyboard presses.

  • CLS (Cumulative Layout Shift) allows QA engineers to measure how much content moves around after first being rendered.

  • FCP (First Contentful Paint). This metric is vital since it measures how long it takes for a page to render the first content on the screen.

  • SI (Speed Index). It allows estimating how quickly content gets displayed during a page load.

  • TTI (Time to Interactive). It measures the responsiveness of a page and helps identify if a page is actually working and if it responds to interactions after a specified loading time.
All in all, Lighthouse performance metrics let engineers estimate the time customers have to wait before a web page is ready for interactions. It also tracks if the content and layout are neatly rendered, easy to interact with, and needs adequate time for loading.

As a result of web application performance testing, you receive a report on what is working great and where you need improvements.
Mobile Performance Testing Is Also Vital
Almost 60% of the world's population prefer mobile devices to surf the web, looking for products and services. If you wish to engage more customers, you need to focus on how your web e-commerce solution functions on mobile devices.
Your e-commerce website may work great on desktop, but it doesn't mean the performance will be equally good on mobile. On average, the loading time of a web page is 87.84% longer for mobile devices. You should offer customers easy-to-interact on-page elements, like those they can enjoy on desktop.

For example, if content moves when a customer is about to click it on mobile, it is a bad sign. Test engineers will use the tool to measure the amount of content that moves around after first being rendered, and if the Lighthouse performance score is over 0.1, they will report the issue.
You may need performance testing for web applications on desktop and mobile to offer customers as great a shopping experience as they wish. If you charge QA professionals to audit your web e-commerce solution, that might help mitigate risks of high churn rate or negative user feedback and prevent financial losses.

Web page load is not a single moment in time, and software QA engineers use many metrics to get a full assessment. The Lighthouse performance testing tool is a reliable assistant. It makes capturing errors in multiple moments easier and offers ways to enhance the load experience and remove any obstacle that may deter customers.