PerformanceEventTiming: toJSON() method

Baseline 2025

Newly available

Since December 2025, this feature works across the latest devices and browser versions. This feature might not work in older devices or browsers.

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

Syntax

toJSON()

Parameters

None.

Return value

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

The JSON doesn't contain the target property because it is of type Node, which doesn't provide a toJSON() operation.

Examples

Using the toJSON method

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

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

observer.observe({ type: "event", buffered: true });

This would log a JSON object like so:

json
{
  "name": "dragover",
  "entryType": "event",
  "startTime": 67090751.599999905,
  "duration": 128,
  "processingStart": 67090751.70000005,
  "processingEnd": 67090751.900000095,
  "cancelable": true
}

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