VisibilityStateEntry
Limited availability
This feature is not Baseline because it does not work in some of the most widely-used browsers.
Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.
The VisibilityStateEntry interface provides timings of page visibility state changes, i.e., when a tab changes from the foreground to the background or vice versa.
This can be used to pinpoint visibility changes on the performance timeline, and cross-reference them against other performance entries such as "first-contentful-paint" (see PerformancePaintTiming).
There are two key visibility state change times that this API reports on:
visible: The time when the page becomes visible (i.e., when its tab moves into the foreground).hidden: The time when the pages become hidden (i.e., when its tab moves into the background).
The performance timeline will always have a "visibility-state" entry with a startTime of 0 and a name representing the initial page visibility state.
Note:
Like other Performance APIs, this API extends PerformanceEntry.
Instance properties
This interface has no properties but it extends the properties of PerformanceEntry by qualifying and constraining them as follows:
PerformanceEntry.entryTypeExperimental-
Returns
"visibility-state". PerformanceEntry.nameExperimental-
Returns either
"visible"or"hidden". PerformanceEntry.startTimeExperimental-
Returns the
timestampwhen the visibility state change occurred. PerformanceEntry.durationExperimental-
Returns 0.
Instance methods
This interface has no methods.
Examples
Basic usage
The following function could be used to log a table of all "visibility-state" performance entries to the console:
function getVisibilityStateEntries() {
const visibilityStateEntries =
performance.getEntriesByType("visibility-state");
console.table(visibilityStateEntries);
}
Correlating visibility state changes with paint timing
The below function gets a reference to all "visibility-state" entries and the "first-contentful-paint" entry, then uses Array.some() to test whether any of the "hidden" visibility entries occurred before the first contentful paint:
function wasHiddenBeforeFirstContentfulPaint() {
const fcpEntry = performance.getEntriesByName("first-contentful-paint")[0];
const visibilityStateEntries =
performance.getEntriesByType("visibility-state");
return visibilityStateEntries.some(
(e) => e.startTime < fcpEntry.startTime && e.name === "hidden",
);
}
Specifications
| Specification |
|---|
| HTML # the-visibilitystateentry-interface |
Browser compatibility
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