How to use PHP WebDriver to test page loading time

With the continuous popularity of the Internet, page loading time, as an important indicator of user experience, is of great significance for website optimization and performance tuning. During the testing process, how to accurately measure page loading time becomes an important issue. This article will introduce how to use PHP WebDriver to test page loading time.

1. Introduction to PHP WebDriver

PHP WebDriver is a PHP development tool based on Selenium WebDriver. It controls the browser to perform page operations by calling the browser's underlying driver. Using PHP WebDriver, you can implement automated testing, crawling and other functions of web pages.

2. Test method of page loading time

Before testing the page loading time, we need to understand several concepts:

• First rendering time (First Paint Time): refers to the time difference between when the browser starts rendering the page and when the first pixel appears on the page.
• First Contentful Paint: refers to the time when the first batch of meaningful content appears on the page.
• First Interactive Time: refers to the time when the main script on the page has been loaded and the user can start interacting.
• Page Load Time: refers to the time when all resources on the page are completely loaded and the script is executed.

Based on the above concepts, the following tests can be performed:

1. First Paint Time test

When the browser starts drawing Page, we can use 'first-paint' in the Performance Timing API to get the first rendering time. The code is as follows:

$driver->get('http://www.baidu.com');
$performance = $driver->executeScript('return window.performance.timing');
$firstPaint = $performance['responseStart'] - $performance['navigationStart'];
echo "First Paint Time: " . $firstPaint . "ms
";

2. First Contentful Paint Test

Due to browser caching, the first rendering may not be complete, so we need a more accurate method to test First Contentful Paint (FCP).

Using the browser's Observer API to obtain the timestamp of recent content changes, you can implement the function of measuring FCP. The sample code is as follows:

$driver->get('http://www.baidu.com');
$driver->executeScript('function observerCallback(entries) {
  entries.forEach(entry => {
      if(entry.entryType == "paint" && entry.name == "first-contentful-paint") {
        console.log(entry.startTime);
        return entry.startTime;
      }
  });
}
var observer = new PerformanceObserver(observerCallback);
observer.observe({entryTypes: ["paint"]});');

3. First Interactive Time Time) test

For First Interactive Time, you can test it by monitoring the DOMContentLoaded event. The sample code is as follows:

$driver->get('http://www.baidu.com');
$driver->executeScript('function ti() {
    var ti = window.performance.timing.domContentLoadedEventEnd - window.performance.timing.navigationStart;
    console.log(ti);
    return ti;
}
return {ti: ti()};');

4. Page Load Time Test

The full page loading time can be obtained through the navigation timing API. The sample code is as follows:

$driver->get('http://www.baidu.com');
$performance = $driver->executeScript('return window.performance.timing');
$pageLoadTime = $performance['loadEventEnd'] - $performance['navigationStart'];
echo "Page Load Time: " . $pageLoadTime . "ms
";

3. Conclusion

The page loading time can be tested through PHP WebDriver Help us better understand page performance and provide important reference for optimizing the website. This article introduces how to use PHP WebDriver to test page loading time. Readers can implement it accordingly based on their actual situation.

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