Web/API/PerformanceEntry/startTime

The startTime property returns the first recorded timestamp of the performance entry.

Note: This feature is available in Web Workers.

The value returned by this property depends on the performance entry's type:

"frame" - returns the timestamp when the frame was started.
"mark" - returns the timestamp when the mark was created by a call to performance.mark().
"measure" - returns the timestamp when the measure was created by a call to performance.measure().
"navigation" - returns the timestamp with a value of "0".
"resource" - returns the timestamp immediately before the browser starts fetching the resource.

This property is Read only .

Syntax

entry.startTime;

Return value

A DOMHighResTimeStamp representing the first timestamp when the performance entry was created.

Note: if the performance entry has an entryType of "resource" (i.e. the entry is a PerformanceResourceTiming object), this property returns the PerformanceEntry.fetchStart timestamp.

Example

The following example shows the use of the startTime property.

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 'startTime' in that specification.	Candidate Recommendation
Performance TimelineThe definition of 'startTime' in that specification.	Recommendation	Initial definition.

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
`startTime`	Chrome Full support Yes	Edge Full support 12	Firefox Full support Yes	IE Full support Yes	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

PerformanceEntry.startTime by Mozilla Contributors is licensed under CC-BY-SA 2.5.