Performance: toJSON() method

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since April 2021.

Note: This feature is available in Web Workers.

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

Syntax

toJSON()

Parameters

None.

Return value

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

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

Note: The JSON object contains the serialization of the deprecated performance.timing and performance.navigation properties. To get a JSON representation of the newer PerformanceNavigationTiming interface, call PerformanceNavigationTiming.toJSON() instead.

Examples

Using the toJSON method

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

performance.toJSON();

This would log a JSON object like so:

json

{
  "timeOrigin": 1668077531367.4,
  "timing": {
    "connectStart": 1668077531372,
    "navigationStart": 1668077531367,
    "secureConnectionStart": 0,
    "fetchStart": 1668077531372,
    "domContentLoadedEventStart": 1668077531580,
    "responseStart": 1668077531372,
    "domInteractive": 1668077531524,
    "domainLookupEnd": 1668077531372,
    "responseEnd": 1668077531500,
    "redirectStart": 0,
    "requestStart": 1668077531372,
    "unloadEventEnd": 0,
    "unloadEventStart": 0,
    "domLoading": 1668077531512,
    "domComplete": 1668077531585,
    "domainLookupStart": 1668077531372,
    "loadEventStart": 1668077531585,
    "domContentLoadedEventEnd": 1668077531580,
    "loadEventEnd": 1668077531585,
    "redirectEnd": 0,
    "connectEnd": 1668077531372
  },
  "navigation": {
    "type": 0,
    "redirectCount": 0
  }
}

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

Specifications

Specification
High Resolution Time # dom-performance-tojson