Conducting Performance and Load Testing

Tutorial 4 of 5

1. Introduction

1.1 Brief explanation of the tutorial's goal

This tutorial aims to guide you on how to conduct performance and load testing on HTML websites. By the end of this tutorial, you will have a clear understanding of the tools, techniques, and best practices used in this critical aspect of web development.

1.2 What the user will learn

You will learn the following:

The fundamental concepts of performance and load testing.
How to use essential tools for running these tests.
Best practices to ensure your website is optimally performing under different loads.

1.3 Prerequisites

To make the most out of this tutorial, you should have:

Basic understanding of HTML and web development.
A functional HTML website or web page to use for testing.

2. Step-by-Step Guide

2.1 Explanation of concepts

Performance and load testing are essential to ensure that your website can handle a large number of users without compromising its functionality or performance.

Performance testing: This involves checking how fast your web pages load under normal conditions.
Load testing: This involves checking the maximum amount of load (users, traffic) your website can handle before performance starts to degrade.

2.2 Examples and Best Practices

2.2.1 Google Lighthouse

Google Lighthouse is an open-source, automated tool for improving the quality of web pages. It has audits for performance, accessibility, progressive web apps, SEO, and more.

To use Google Lighthouse:

Open your website on Google Chrome.
Open Chrome DevTools by right-clicking and selecting Inspect.
Go to Lighthouse tab.
Click Generate report.

Best Practice: Run multiple tests to get an average score, as one-time scores can be affected by network conditions.

3. Code Examples

Typically, performance and load testing do not involve writing code but using existing tools. However, here's how you can adjust a simple HTML page's load time.

Code Snippet:

<html>
<head>
    <script type="text/javascript">
        function loadTime() {
            window.onload = function(){
                setTimeout(function(){
                    var t = performance.timing;
                    console.log('Page load time is '+ (t.loadEventEnd - t.responseEnd));
                }, 0);
            }
        }
    </script>
</head>
<body onload="loadTime()">
    <h1>Hello World!</h1>
</body>
</html>

Explanation: This script calculates the time it takes for the page to fully load and logs it in the console.

Expected Output: 'Page load time is X' (X being the time in milliseconds)

4. Summary

In this tutorial, we covered the basics of performance and load testing. We learned the importance of these tests and how to conduct them using Google Lighthouse. The next step is to learn about more advanced testing techniques and tools like JMeter.

5. Practice Exercises

Exercise: Use Google Lighthouse to get a performance score for your website. Try to optimize your website to get a score above 90.
- Solution: The optimization techniques will depend on the specific issues highlighted in the Lighthouse report. It could involve reducing image sizes, removing unnecessary JavaScript, etc.
Exercise: Write a JavaScript function to measure the time it takes for an image to load on your webpage.
- Solution: This involves using the Date.now() function when the image starts loading and when it finishes loading. The difference between these two times is the load time.

Remember, testing is an ongoing process. Always monitor your website's performance and adjust as necessary. Happy testing!