PerformanceObserver()
The PerformanceObserver()
constructor creates a new
PerformanceObserver
object with the given observer callback
.
The observer callback is invoked when performance entry
events are recorded for the
entry types that have been
registered, via the observe()
method.
Syntax
new PerformanceObserver(callback)
Parameters
callback
-
A
PerformanceObserverCallback
callback that will be invoked when observed performance events are recorded. When the callback is invoked, its first parameter is a list of performance observer entries and the second parameter is theobserver
object.
Return value
A new PerformanceObserver
object which will call the specified
callback
when observed performance events occur.
Examples
const observer = new PerformanceObserver(function(list, obj) {
const entries = list.getEntries();
for (let i=0; i < entries.length; i++) {
// Process "mark" and "frame" events
}
});
observer.observe({entryTypes: ["mark", "frame"]});
function perf_observer(list, observer) {
// Process the "measure" event
}
const observer2 = new PerformanceObserver(perf_observer);
observer2.observe({entryTypes: ["measure"]});
Specifications
Specification |
---|
Performance Timeline # dom-performanceobserver-constructor |
Browser compatibility
BCD tables only load in the browser