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• 特性
• 方法
• 范例
• 规范
• 浏览器兼容性
• 相关话题

LargestContentfulPaint interface of the Largest Contentful Paint API provides details about the largest image or text paint before user input on a web page. The timing of this paint is a good heuristic for when the main page content is available during load.

特性

LargestContentfulPaint.element

The element that is the current largest contentful paint.

LargestContentfulPaint.renderTime

The time the element was rendered to the screen. May not be available if the element is a cross-origin image loaded without the Timing-Allow-Origin 头。

LargestContentfulPaint.loadTime

The time the element was loaded.

LargestContentfulPaint.size

The intrinsic size of the element returned as the area (width * height).

LargestContentfulPaint.id

The id of the element. This property returns an empty string when there is no id.

LargestContentfulPaint.url

If the element is an image, the request url of the image.

方法

LargestContentfulPaint.toJSON()

Returns the above properties as JSON.

范例

The following example shows how to create a PerformanceObserver that listens for largest-contentful-paint entries and logs the LCP value to the console.

This example also demonstrates how to include buffered entries (those that ocurred before observer() was called), which is done by setting the buffered 选项到 true .

Note that in this example data is only sent to the server when the user leaves the tab.

// Catch errors since some browsers throw when using the new `type` option.
// https://bugs.webkit.org/show_bug.cgi?id=209216
try {
  let lcp;
  const po = new PerformanceObserver((entryList) => {
    const entries = entryList.getEntries();
    const lastEntry = entries[entries.length - 1];
    // Update `lcp` to the latest value, using `renderTime` if it's available,
    // otherwise using `loadTime`. (Note: `renderTime` may not be available on
    // image elements loaded cross-origin without the `Timing-Allow-Origin` header.)
    lcp = lastEntry.renderTime || lastEntry.loadTime;
  });
  po.observe({type: 'largest-contentful-paint', buffered: true});
  // Send data to the server.
  addEventListener('visibilitychange', function fn() {
    if (lcp && document.visibilityState === 'hidden') {
      console.log('LCP:', lcp);
      removeEventListener('visibilitychange', fn, true);
    }
  }, true);
} catch (e) {
  // Do nothing if the browser doesn't support this API.
}
					

规范

规范	状态	注释
Largest Contentful Paint The definition of 'LargestContentfulPaint' in that specification.	编者草案	初始定义。

浏览器兼容性

The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request. 更新 GitHub 上的兼容性数据

	桌面						移动
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
LargestContentfulPaint	Chrome 77	Edge 80	Firefox No	IE No	Opera Yes	Safari No	WebView Android 77	Chrome Android 77	Firefox Android No	Opera Android Yes	Safari iOS No	Samsung Internet Android 12.0
element	Chrome 77	Edge 80	Firefox No	IE No	Opera Yes	Safari No	WebView Android 77	Chrome Android 77	Firefox Android No	Opera Android Yes	Safari iOS No	Samsung Internet Android 12.0
id	Chrome 77	Edge 80	Firefox No	IE No	Opera Yes	Safari No	WebView Android 77	Chrome Android 77	Firefox Android No	Opera Android Yes	Safari iOS No	Samsung Internet Android 12.0
loadTime	Chrome 77	Edge 80	Firefox No	IE No	Opera Yes	Safari No	WebView Android 77	Chrome Android 77	Firefox Android No	Opera Android Yes	Safari iOS No	Samsung Internet Android 12.0
renderTime	Chrome 77	Edge 80	Firefox No	IE No	Opera Yes	Safari No	WebView Android 77	Chrome Android 77	Firefox Android No	Opera Android Yes	Safari iOS No	Samsung Internet Android 12.0
size	Chrome 77	Edge 80	Firefox No	IE No	Opera Yes	Safari No	WebView Android 77	Chrome Android 77	Firefox Android No	Opera Android Yes	Safari iOS No	Samsung Internet Android 12.0
toJSON	Chrome 77	Edge 80	Firefox No	IE No	Opera Yes	Safari No	WebView Android 77	Chrome Android 77	Firefox Android No	Opera Android Yes	Safari iOS No	Samsung Internet Android 12.0
url	Chrome 77	Edge 80	Firefox No	IE No	Opera Yes	Safari No	WebView Android 77	Chrome Android 77	Firefox Android No	Opera Android Yes	Safari iOS No	Samsung Internet Android 12.0

图例

完整支持

完整支持

不支持

不支持

元数据

• 最后修改： May 15, 2020