PerformanceEntry

The PerformanceEntry object encapsulates a single performance metric that is part of the performance timeline. A performance entry can be directly created by making a performance mark or measure (for example by calling the mark() method) at an explicit point in an application. Performance entries are also created in indirect ways such as loading a resource (such as an image).

PerformanceEntry instances will always be one of the following subtypes:

Note:

This feature is available in Web Workers.

Properties

PerformanceEntry.name Read only
A value that further specifies the value returned by the PerformanceEntry.entryType property. The value of both depends on the subtype. See property page for valid values.
PerformanceEntry.entryType Read only
A DOMString representing the type of performance metric such as, for example, "mark". See property page for valid values.
PerformanceEntry.startTime Read only
A DOMHighResTimeStamp representing the starting time for the performance metric.
PerformanceEntry.duration Read only
A DOMHighResTimeStamp representing the time value of the duration of the performance event.

Methods

PerformanceEntry.toJSON()
Returns a JSON representation of the PerformanceEntry object.

Example

The following example checks all PerformanceEntry properties to see if the browser supports them and if so, write their values to the console.

function print_PerformanceEntries() {
  // Use getEntries() to get a list of all performance entries
  var p = performance.getEntries();
  for (var i=0; i < p.length; i++) {
    console.log("PerformanceEntry[" + i + "]");
    print_PerformanceEntry(p[i]);
  }
}
function print_PerformanceEntry(perfEntry) {
  var properties = ["name",
                    "entryType",
                    "startTime",
                    "duration"];

  for (var i=0; i < properties.length; i++) {
    // Check each property
    var supported = properties[i] in perfEntry;
    if (supported) {
      var value = perfEntry[properties[i]];
      console.log("... " + properties[i] + " = " + value);
    } else {
      console.log("... " + properties[i] + " is NOT supported");
    }
  }
}

Specifications

Specification Status Comment
Resource Timing Level 3 Editor's Draft
Resource Timing Level 2 Working Draft
Resource Timing Level 1 Candidate Recommendation Adds the PerformanceResourceTiming interface and the resource value for entryType.
Navigation Timing Level 2 Working Draft
Navigation Timing Recommendation Adds the PerformanceNavigationTiming interface and the navigation value for entryType.
User Timing Level 2 Working Draft
User Timing Recommendation Adds the PerformanceMark and PerformanceMeasure interfaces as well as the mark and measure values for entryType.
Frame Timing Draft Adds the PerformanceFrameTiming interface and the frame value for entryType.
Performance Timeline Level 2
The definition of 'PerformanceEntry' in that specification.
Candidate Recommendation Added toJSON() serializer method.
Performance Timeline
The definition of 'PerformanceEntry' in that specification.
Recommendation Initial definition.

Browser compatibility

BCD tables only load in the browser