Web/API/PerformanceEntry/toJSON

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

Note: This feature is available in Web Workers.

Syntax

json = perfEntry.toJSON();

Arguments

None

Return value

json: A JSON object that is the serialization of the PerformanceEntry object.

Example

The following example shows the use of the toJSON() method.

function run_PerformanceEntry() {
  log("PerformanceEntry support ...");

  if (performance.mark === undefined) {
    log("... performance.mark Not supported");
    return;
  }

  // Create some performance entries via the mark() method
  performance.mark("Begin");
  do_work(50000);
  performance.mark("End");

  // Use getEntries() to iterate through the each entry
  var p = performance.getEntries();
  for (var i=0; i < p.length; i++) {
    log("Entry[" + i + "]");
    check_PerformanceEntry(p[i]);
  }
}
function check_PerformanceEntry(obj) {
  var properties = ["name", "entryType", "startTime", "duration"];
  var methods = ["toJSON"];

  for (var i=0; i < properties.length; i++) {
    // check each property
    var supported = properties[i] in obj;
    if (supported)
      log("..." + properties[i] + " = " + obj[properties[i]]);
    else 
      log("..." + properties[i] + " = Not supported");
  }
  for (var i=0; i < methods.length; i++) {
    // check each method
    var supported = typeof obj[methods[i]] == "function";
    if (supported) {
      var js = obj[methods[i]]();
      log("..." + methods[i] + "() = " + JSON.stringify(js));
    } else {
      log("..." + methods[i] + " = Not supported");
    }
  }
}

Specifications

Specification	Status	Comment
Performance Timeline Level 2The definition of 'toJSON' in that specification.	Candidate Recommendation	Initial definition of `toJSON()` method.

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`toJSON`	Chrome Full support Yes	Edge Full support 16	Firefox Full support Yes	IE No support No	Opera Full support Yes	Safari Full support 11	WebView Android Full support Yes	Chrome Android Full support Yes	Firefox Android Full support 25	Opera Android Full support Yes	Safari iOS Full support 11	Samsung Internet Android Full support Yes

Legend

Full support: Full support
No support: No support

PerformanceEntry.toJSON() by Mozilla Contributors is licensed under CC-BY-SA 2.5.