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

var observer = new PerformanceObserver(callback);

Parameters

callback

A PerformanceObserverCallback callback that will be invoked when observered performance events are recorded. When the callback is invoked, its first parameter is a list of performance observer entries and the second parameter is the observer object.

Example

var observer = new PerformanceObserver(function(list, obj) {
  var entries = list.getEntries();
  for (var 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 
}
var observer2 = new PerformanceObserver(perf_observer);
observer2.observe({entryTypes: ["measure"]});

Specifications

Browser compatibility

[1] Only activated in Nightly builds. Controlled by the dom.enable_performance_observer preference.