The toJSON() method of the PerformanceElementTiming interface is a standard serializer. It returns a JSON representation of the object's properties.


var json = PerformanceElementTiming.toJSON();

Return value

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


In this example calling entry.toJSON() returns a JSON representation of the PerformanceElementTiming object, with the information about the image element.

<img src="image.jpg" alt="a nice image" elementtiming="big-image" id="myImage">
const observer = new PerformanceObserver((list) => {
  let entries = list.getEntries().forEach(function (entry) {
    if (entry.identifier === "big-image") {
observer.observe({ entryTypes: ["element"] });

This example uses the PerformanceObserver interface to create a list of performance measurement events. In our case we observe the PerformanceEntry.entrytype element in order to use the PerformanceElementTiming interface.


Specification Status Comment
Element Timing
The definition of 'PerformanceElementTiming.toJson()' in that specification.
Editor's Draft Initial definition.

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