PerformanceLongTaskTiming: toJSON() method

Limited availability

This feature is not Baseline because it does not work in some of the most widely-used browsers.

Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

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

Syntax

toJSON()

Parameters

None.

Return value

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

Examples

Using the toJSON method

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

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

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

This would log a JSON object like so:

json
{
  "name": "self",
  "entryType": "longtask",
  "startTime": 183,
  "duration": 60,
  "attribution": [
    {
      "name": "unknown",
      "entryType": "taskattribution",
      "startTime": 0,
      "duration": 0,
      "containerType": "window",
      "containerSrc": "",
      "containerId": "",
      "containerName": ""
    }
  ]
}

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