Lessons
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Introduction
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Search engine optimization
- Broken links
- Site map
- Micro-markup
- Robots.txt
- References
- Text
- Duplicates
- Basic
- Pictures
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Speed
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Minification
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CSS minification
Minification of JavaScript files
Minification of inline CSS code
Minification of images without loss of quality
Minification of JavaScript files
Unused CSS code
Data optimization:Image URLs
Format of animated images
Unused JavaScript code
Using WebP
Image compression is missing
Video bitrate
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Reducing requests
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An overabundance of small pictures
Ungrouped CSS files
Ungrouped JavaScript files
An overabundance of fonts
Availability of end-to-end CSS, JS files
The presence of a monochrome font
Uploading duplicate files
Using JS facades
Redirecting JavaScript code
Adding lazy loading
Redirect from/to www version
- Fonts
- Loading time
- Server Settings
- Pictures
- The first content
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Minification
- Mobility
- Bugs
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Convenience
- Social networks
- Web Application Manifest
- Favicons
- Basic
- Text readability
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Security
- Encrypted connection
- Exploits
- Vulnerabilities
Preliminary connection
Preliminary connection to the server
Often sites download files from external services. These can be maps or social media widgets. Those, in turn, download data from their sources.
For example, when the Yandex map is displayed on the site, the script is loaded https://api-maps.yandex.ru/services/constructor/1.0/js /, and he requests a photo of the cards from the address https://core-renderer-tiles.maps.yandex.net. Thus, after loading the script, he spends time connecting to the site that gives out pictures.
But you can speed up the work of maps by adding a special code to the page that will create a connection to the address https://core-renderer-tiles.maps.yandex.net even before loading the script itself.
<link rel="preconnect" href="https://core-renderer-tiles.maps.yandex.net" crossorigin />
<link rel="dns-prefetch" href="https://core-renderer-tiles.maps.yandex.net" />
This way you will speed up the loading of the map from a few tens to hundreds of milliseconds.
But it only makes sense if the map or social media widget is on the first screen. In all other cases, postpone loading the map until the rest of the page loads, or until the user scrolls through the page and is about to see the map.
Preloading files
Preloading files does not help to load the page faster, but only helps to display meaningful content faster. Therefore, there is no point in preloading CSS and JavaScript. You will not be able to preload pictures and videos, since it is not possible to upload a picture in accordance with DPR.
It is worth preloading font files in order to display the text content of the page as quickly as possible.