The toJSON() method is a serializer; it returns a JSON representation of the PerformanceEntry object.

None.

A JSON object that is the serialization of the PerformanceEntry object.

In this example, calling entry.toJSON() returns a JSON representation of the PerformanceMark object.

performance.mark("debug-marker", {
  detail: "debugging-marker-123",
});

const observer = new PerformanceObserver((list) => {
  list.getEntries().forEach((entry) => {
    console.log(entry.toJSON());
  });
});

observer.observe({ entryTypes: ["mark"] });

This would log a JSON object like so:

{
  "name": "debug-marker",
  "entryType": "mark",
  "startTime": 158361,
  "duration": 0
}

Note that it doesn't contain PerformanceMark's detail property.

To get a JSON string, you can use JSON.stringify(entry) directly; it will call toJSON() automatically.

• JSON