PerformanceResourceTiming: 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 October 2017.
Note: This feature is available in Web Workers.
The toJSON() method of the PerformanceResourceTiming interface is a serializer; it returns a JSON representation of the PerformanceResourceTiming object.
Syntax
js
toJSON() Parameters
None.
Return value
A JSON object that is the serialization of the PerformanceResourceTiming object.
Examples
Using the toJSON method
In this example, calling entry.toJSON() returns a JSON representation of the PerformanceResourceTiming object.
js
const observer = new PerformanceObserver((list) => { list.getEntries().forEach((entry) => { console.log(entry.toJSON()); }); }); observer.observe({ type: "resource", buffered: true }); This would log a JSON object like so:
json
{ "name": "https://upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/31px-Commons-logo.svg.png", "entryType": "resource", "startTime": 110.80000001192093, "duration": 11.599999994039536, "initiatorType": "img", "nextHopProtocol": "h2", "renderBlockingStatus": "non-blocking", "workerStart": 0, "redirectStart": 0, "redirectEnd": 0, "fetchStart": 110.80000001192093, "domainLookupStart": 110.80000001192093, "domainLookupEnd": 110.80000001192093, "connectStart": 110.80000001192093, "connectEnd": 110.80000001192093, "secureConnectionStart": 110.80000001192093, "requestStart": 117.30000001192093, "responseStart": 120.40000000596046, "responseStatus": 200, "responseEnd": 122.40000000596046, "transferSize": 0, "encodedBodySize": 880, "decodedBodySize": 880, "serverTiming": [ { "name": "cache", "duration": 0, "description": "hit-front" }, { "name": "host", "duration": 0, "description": "cp3061" } ] } To get a JSON string, you can use JSON.stringify(entry) directly; it will call toJSON() automatically.
Specifications
| Specification |
|---|
| Resource Timing # dom-performanceresourcetiming-tojson |