new PerformanceObserver(callback)
callback
<Function>list
<PerformanceObserverEntryList>observer
<PerformanceObserver>
当新的 PerformanceEntry
实例被添加到性能时间线时,则 PerformanceObserver
对象会提供通知。
const {
performance,
PerformanceObserver,
} = require('node:perf_hooks');
const obs = new PerformanceObserver((list, observer) => {
console.log(list.getEntries());
performance.clearMarks();
performance.clearMeasures();
observer.disconnect();
});
obs.observe({ entryTypes: ['mark'], buffered: true });
performance.mark('test');
因为 PerformanceObserver
实例引入了它们自己的额外性能开销,实例不应无限期地订阅通知。
一旦不再需要观察者,则用户应立即断开观察者的连接。
当 PerformanceObserver
接收到有关新的 PerformanceEntry
实例的通知时,则会调用 callback
。
回调接收到 PerformanceObserverEntryList
实例和对 PerformanceObserver
的引用。
callback
<Function>list
<PerformanceObserverEntryList>observer
<PerformanceObserver>
PerformanceObserver
objects provide notifications when new
PerformanceEntry
instances have been added to the Performance Timeline.
const {
performance,
PerformanceObserver,
} = require('node:perf_hooks');
const obs = new PerformanceObserver((list, observer) => {
console.log(list.getEntries());
performance.clearMarks();
performance.clearMeasures();
observer.disconnect();
});
obs.observe({ entryTypes: ['mark'], buffered: true });
performance.mark('test');
Because PerformanceObserver
instances introduce their own additional
performance overhead, instances should not be left subscribed to notifications
indefinitely. Users should disconnect observers as soon as they are no
longer needed.
The callback
is invoked when a PerformanceObserver
is
notified about new PerformanceEntry
instances. The callback receives a
PerformanceObserverEntryList
instance and a reference to the
PerformanceObserver
.