how to optimize the performance of web pages? For front-end performance optimization, here are five tips for improving website loading speed:
- compress and merge files: compress HTML, CSS, JavaScript, and then merge them to reduce HTTP requests.
- Latency loading: loads content only when needed.
- lazy loading: images and other media are loaded only when the user scrolls the page.
- use caching: use browser caching to reduce resource loading time.
- compressed images: use compressed image formats, such as JPEG, to reduce file size and speed up loading.
1. Compress and merge files
you can use tools and plug-ins (such as Gulp, Grunt, Webpack, and so on) to automatically compress and merge files.
HTML compression:
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>HTML compression exampl</title>
</head>
<body>
<h1>This is the title.</h1>
<p>This is a passage.</p>
</body>
</html>
CSS compression:
body {
background-color: #f8f8f8;
font-family: Arial, sans-serif;
font-size: 16px;
}
h1 {
color: #333;
font-size: 28px;
}
p {
color: #666;
font-size: 18px;
}
JavaScript compression:
(function() {
var message = "Hello World!";
console.log(message);
}());
2. Delayed loading
delayed loading can be achieved using JavaScript.
<img data-src="image.jpg" alt="Picture">
<script>
// wait for the page to be fully loaded before executing the script
window.onload = function() {
// get all picture tags
var images = document.querySelectorAll('img[data-src]');
// traversing the picture tag
Array.prototype.forEach.call(images, function(image) {
// modify src
image.setAttribute('src', image.getAttribute('data-src'));
});
};
</script>
3. Lazy load
lazy loading can be implemented using JavaScript and plug-ins. Here we use the jQuery plug-in to implement lazy loading.
<img data-src="image.jpg" alt="Picture">
<script src="https://code.jquery.com/jquery-3.5.1.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery.lazyload/1.9.1/jquery.lazyload.min.js"></script>
<script>
$(function() {
$("img").lazyload({
effect: "fadeIn",
threshold: 200
});
});
</script>
4. Use caching
you can use HTTP caching to cache resources to reduce load time.
Server-side setting cache:
<?php
$expires = 60 * 60 * 24 * 30; // 30 days
header("Cache-Control: max-age={$expires}, public");
header("Expires: " . gmdate("D, d M Y H:i:s", time() + $expires) . " GMT");
?>
client setting cache:
<img src="image.jpg" alt="Picture" width="300" height="200" />
<script>
if ('caches' in window && 'fetch' in window) { // determine whether caching and fetch API are supported
caches.match('image.jpg').then(function(response) {
if (response) { // load pictures from cache
var img = document.querySelector('img');
img.src = response.url;
} else { // request the picture and cache it
fetch('image.jpg').then(function(response) {
return caches.open('my-cache-name').then(function(cache) {
cache.put('image.jpg', response.clone());
var img = document.querySelector('img');
img.src = response.url;
});
});
}
});
}
</script>
5. Compressed image
you can use tools and online sites to compress images, such as TinyPNG, Kraken, and so on.
<img src="image.jpg" alt="Picture" width="300" height="200" />
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