內容簡介
### 總結:
這個外掛通過優化圖片的加載，特別是 LCP（最大內容繪製時間）元素，包括 img 元素和帶有 CSS 背景圖像的元素。它還通過捕獲每個斷點的 LCP 元素來實現增強。此外，通過確保在任何斷點的初始視口中顯示的圖像中省略 loading=lazy，從而優化圖像加載。
### 問題與答案:
- 外掛的主要功能是什麼？
- 優化圖片的加載，尤其是 LCP 元素。
- 在哪些裝置上，loading=lazy 會被忽略？
- 在以下視窗組中：<br>
- 0-320 (小型智能手機)
- 321-480 (普通智能手機)
- 481-576 (平板電腦)
- 大於576 (桌面)
- 這個外掛是否能立即生效？
- 不是，由於需要收集 URL 指標，因此需要真正的訪客來優化頁面，所以在啟用外掛後不會立即看到優化效果。
- 為什麽這個外掛沒有設置和用戶界面？
- 因為它旨在無需任何配置即可運行。
- 這個外掛需要依賴哪個外掛？
- 需要 Optimization Detective 外掛作為依賴。
外掛標籤
開發者團隊
原文外掛簡介
This plugin optimizes the loading of images (and videos) with prioritization to improve Largest Contentful Paint (LCP), lazy loading, and more accurate image size selection.
The current optimizations include:
Add breakpoint-specific fetchpriority=high preload links (both as LINK[rel=preload] elements and Link response headers) for image URLs of LCP elements:
An IMG element, including the srcset/sizes attributes supplied as imagesrcset/imagesizes on the LINK.
The first SOURCE element with a type attribute in a PICTURE element. (Art-directed PICTURE elements using media queries are not supported.)
An element with a CSS background-image inline style attribute.
An element with a CSS background-image applied with a stylesheet (when the image is from an allowed origin).
A VIDEO element’s poster image.
Ensure fetchpriority=high is only added to an IMG when it is the LCP element across all responsive breakpoints.
Add fetchpriority=low to IMG tags which appear in the initial viewport but are not visible, such as when they are subsequent carousel slides.
Lazy loading:
Apply lazy loading to IMG tags based on whether they appear in any breakpoint’s initial viewport.
Implement lazy loading of CSS background images added via inline style attributes.
Lazy-load VIDEO tags by setting the appropriate attributes based on whether they appear in the initial viewport. If a VIDEO is the LCP element, it gets preload=auto; if it is in an initial viewport, the preload=metadata default is left; if it is not in an initial viewport, it gets preload=none. Lazy-loaded videos also get initial preload, autoplay, and poster attributes restored when the VIDEO is going to enter the viewport.
Responsive image sizes:
Ensure sizes=auto is set on IMG tags after setting correct lazy-loading (above).
~~Compute the sizes attribute using the widths of an image collected from URL Metrics for each breakpoint (when not lazy-loaded since then handled by sizes=auto).~~ (This has been removed due to an issue; use Enhanced Responsive Images instead.)
Reduce the size of the poster image of a VIDEO from full size to the size appropriate for the maximum width of the video (on desktop).
This plugin requires the Optimization Detective plugin as a dependency. Please refer to that plugin for additional background on how this plugin works as well as additional developer options.
👉 Note: This plugin optimizes pages for actual visitors, and it depends on visitors to optimize pages. As such, you won’t see optimizations applied immediately after activating the plugin. Please wait for URL Metrics to be gathered for both mobile and desktop visits. And since administrator users are not normal visitors typically, optimizations are not applied for admins by default.
Your site must have the REST API accessible to unauthenticated frontend visitors since this is how metrics are collected about how a page should be optimized. There are currently no settings and no user interface for this plugin since it is designed to work without any configuration.
