LargestContentfulPaint

The 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.

Properties

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 header.
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.

Methods

LargestContentfulPaint.toJSON()
Returns the above properties as JSON.

Examples

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 option to 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.
}

Specifications

Specification Status Comment
Largest Contentful Paint
The definition of 'LargestContentfulPaint' in that specification.
Editor's Draft Initial definition.

Browser compatibility

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
LargestContentfulPaintChrome Full support 77Edge Full support 80Firefox No support NoIE No support NoOpera Full support YesSafari No support NoWebView Android Full support 77Chrome Android Full support 77Firefox Android No support NoOpera Android Full support YesSafari iOS No support NoSamsung Internet Android Full support 12.0
elementChrome Full support 77Edge Full support 80Firefox No support NoIE No support NoOpera Full support YesSafari No support NoWebView Android Full support 77Chrome Android Full support 77Firefox Android No support NoOpera Android Full support YesSafari iOS No support NoSamsung Internet Android Full support 12.0
idChrome Full support 77Edge Full support 80Firefox No support NoIE No support NoOpera Full support YesSafari No support NoWebView Android Full support 77Chrome Android Full support 77Firefox Android No support NoOpera Android Full support YesSafari iOS No support NoSamsung Internet Android Full support 12.0
loadTimeChrome Full support 77Edge Full support 80Firefox No support NoIE No support NoOpera Full support YesSafari No support NoWebView Android Full support 77Chrome Android Full support 77Firefox Android No support NoOpera Android Full support YesSafari iOS No support NoSamsung Internet Android Full support 12.0
renderTimeChrome Full support 77Edge Full support 80Firefox No support NoIE No support NoOpera Full support YesSafari No support NoWebView Android Full support 77Chrome Android Full support 77Firefox Android No support NoOpera Android Full support YesSafari iOS No support NoSamsung Internet Android Full support 12.0
sizeChrome Full support 77Edge Full support 80Firefox No support NoIE No support NoOpera Full support YesSafari No support NoWebView Android Full support 77Chrome Android Full support 77Firefox Android No support NoOpera Android Full support YesSafari iOS No support NoSamsung Internet Android Full support 12.0
toJSONChrome Full support 77Edge Full support 80Firefox No support NoIE No support NoOpera Full support YesSafari No support NoWebView Android Full support 77Chrome Android Full support 77Firefox Android No support NoOpera Android Full support YesSafari iOS No support NoSamsung Internet Android Full support 12.0
urlChrome Full support 77Edge Full support 80Firefox No support NoIE No support NoOpera Full support YesSafari No support NoWebView Android Full support 77Chrome Android Full support 77Firefox Android No support NoOpera Android Full support YesSafari iOS No support NoSamsung Internet Android Full support 12.0

Legend

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