Lessons
-
Introduction
-
SEO
- Broken links
- Site map
- Semantic markup
- Robots.txt
- References
- Text
- Duplicates
- Basic
- Pictures
-
Speed
-
Minification
-
Minification of CSS to reduce its volume
Minification of the embedded JavaScript code of the page
Minification of the embedded CSS code of the page
Minification of images without loss of quality
Minification of JavaScript files to reduce its volume
Unused CSS code
Data optimization:Image URLs
Animated image format MP4, WEBM, SVG instead of GIF and WEBP
Unused JavaScript code
Using the WebP format in images
Too high-quality images without using compression
Suitable video bitrate
-
Reducing requests
-
An overabundance of small pictures
Grouping CSS files
Grouping JavaScript files
An overabundance of font files
Availability of end-to-end CSS, JS files
The presence of a monochrome font
Uploading duplicate files
Using JavaScript facades
Redirecting JavaScript code
Adding lazy loading
Redirect from/to www version
- Fonts
- Loading time
- Server Settings
- Pictures
-
The first content
-
The sequence of connecting JavaScript files
Font display mode
Setting up a pre-connection
Removing lazy loading
Long JavaScript code execution time
File upload delayed or on demand
The server is located in the same country where the users of the site live
No requests to another country that cause page loading to be blocked
-
Minification
-
Mobility
-
Screen support
-
Adapting the layout to a Full HD computer monitor
Adapting the layout for a horizontal tablet
Adapting the layout for a horizontal phone
Screenshots for the mini-report
How blocks break the page layout
Adapting the layout to an HD computer monitor
Adapting the layout for a vertical tablet
Adapting the layout for a vertical phone
- Comfort
-
Screen support
- Bugs
-
Convenience
- Social networks
- Web Application Manifest
- Favicons
- Basic
- Text readability
-
Vulnerabilities
- Encrypted connection
- Exploits
- Vulnerabilities
Removing lazy loading
Delayed loading is a great technology. Her task is to speed up the site. This is done by downloading images as they become visible to the user.
Refrain from it in the following cases:
- When loading images located on the first screen. If the image is visible on the first screen, it is better to download it as early as possible. So, the page will load visually faster and the user will start exploring the content earlier, even if the download of the remaining files is in progress.
- When loading small images. These images are used as icons in the interface. It is better to place them directly in CSS or HTML code as a base64 string.
An example of how enabling delayed loading delays the display of images located on the first screen.
Demonstration
PHP code
HTML code
<?php
$mode = $_GET['mode'] ?? '';
?><!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<style>
.product img {
max-width:100%;
}
.product {
position: relative;
}
.product .time {
position: absolute;
left: 5px;
top: 5px;
background-color: #fff;
padding: 1px 4px;
}
.btn {
color: #000;
text-decoration: none;
padding: 5px 10px;
border: 1px solid #000;
border-radius: 5px;
}
.btn:hover {
background-color: #ddd;
}
.btn.active {
background-color: #000;
color: #fff;
}
</style>
<script>
// Функция, которая добавляет на изображение время окончания загрузки
function endLoading(el) {
var time = performance.now()/1000;
el.parentNode.insertAdjacentHTML("beforeend", '<div class="time">'+time+' с</div>');
}
</script>
</head>
<body style="font-family: sans-serif;">
Режим: <a class="btn <?=$mode === '' ? 'active' : ''?>" href="./lazyload_remove.php">Отключённая отложенная загрузка</a> <a class="btn <?=$mode === 'enable' ? 'active' : ''?>" href="./lazyload_remove.php?mode=enable">Включённая отложенная загрузка</a>
<p>Обратите внимание на разницу во времени загрузки изображения.</p>
<div class="product">
<img src="./photo.jpg?t=<?=microtime(true)?>" <?=$mode === 'enable' ? 'loading="lazy"' : ''?> onload="endLoading(this)" />
</div>
<?php for($i = 0; $i < 100;++$i) { ?>
<script src="./10-kb-js.js?t=<?=microtime(true).'.'.$i?>"/></script>
<?php } ?>
</body>
</html>
<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<style>
.product img {
max-width:100%;
}
.product {
position: relative;
}
.product .time {
position: absolute;
left: 5px;
top: 5px;
background-color: #fff;
padding: 1px 4px;
}
.btn {
color: #000;
text-decoration: none;
padding: 5px 10px;
border: 1px solid #000;
border-radius: 5px;
}
.btn:hover {
background-color: #ddd;
}
.btn.active {
background-color: #000;
color: #fff;
}
</style>
<script>
// Функция, которая добавляет на изображение время окончания загрузки
function endLoading(el) {
var time = performance.now()/1000;
el.parentNode.insertAdjacentHTML("beforeend", '<div class="time">'+time+' с</div>');
}
</script>
</head>
<body style="font-family: sans-serif;">
Режим: <a class="btn active" href="./lazyload_remove.php">Отключённая отложенная загрузка</a> <a class="btn " href="./lazyload_remove.php?mode=enable">Включённая отложенная загрузка</a>
<p>Обратите внимание на разницу во времени загрузки изображения.</p>
<div class="product">
<img src="./photo.jpg?t=1770055133.5188" onload="endLoading(this)" />
</div>
<script src="./10-kb-js.js?t=1770055133.5188.0"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.1"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.2"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.3"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.4"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.5"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.6"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.7"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.8"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.9"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.10"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.11"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.12"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.13"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.14"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.15"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.16"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.17"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.18"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.19"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.20"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.21"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.22"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.23"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.24"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.25"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.26"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.27"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.28"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.29"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.30"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.31"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.32"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.33"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.34"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.35"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.36"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.37"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.38"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.39"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.40"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.41"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.42"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.43"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.44"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.45"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.46"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.47"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.48"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.49"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.50"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.51"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.52"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.53"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.54"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.55"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.56"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.57"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.58"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.59"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.60"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.61"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.62"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.63"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.64"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.65"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.66"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.67"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.68"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.69"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.70"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.71"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.72"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.73"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.74"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.75"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.76"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.77"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.78"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.79"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.80"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.81"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.82"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.83"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.84"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.85"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.86"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.87"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.88"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.89"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.90"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.91"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.92"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.93"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.94"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.95"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.96"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.97"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.98"/></script>
<script src="./10-kb-js.js?t=1770055133.5188.99"/></script>
</body>
</html>