PerformanceObserver(callback)Creates and returns a new PerformanceObserver object.
The observer callback is invoked when performance entry events are recorded by performance.mark() or performance.measure() calls for the entry types that have been registered, via the observe() method.
| Name | Type | Description |
|---|---|---|
callback | function |
supportedEntryTypes: Array<string> = ["mark"Returns an array of the entryType values supported by the user agent.
disconnect()Stops the performance observer callback from receiving performance entries.
observe(options)Specifies the set of entry types to observe.
The performance observer's callback function will be invoked when performance entry is recorded for one of the specified entryTypes.
| Name | Type | Description |
|---|---|---|
options | Object | An object with the following possible members: |
function perfObserver(list, observer) {
list.getEntries().forEach((entry) => {
if (entry.entryType === "mark") {
console.log(`${entry.name}'s startTime: ${entry.startTime}`);
}
if (entry.entryType === "measure") {
console.log(`${entry.name}'s duration: ${entry.duration}`);
}
});
}
const observer = new PerformanceObserver(perfObserver);
observer.observe({ entryTypes: ["measure", "mark"] });takeRecords()Returns the current list of performance entries stored in the performance observer, emptying it out.
Array<PerformanceEntry>