PerformanceEntry.duration - Web API 接口参考 编辑

The duration property returns a timestamp that is the duration of the performance entry.

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

• "frame" - returns a timestamp indicating the difference between the startTimes of two successive frames.
• "mark" - returns "0" (a mark has no duration).
• "measure" - returns the timestamp that is the duration of the measure.
• "navigation" - returns the timestamp that is the difference between the PerformanceEntry.loadEventEnd and PerformanceEntry.startTime properties, respectively.例如： entry.entryType "navigation"，entry.duration 3611.26, entry.loadEventEnd 3611.2672285754975, entry.startTime 0；
• "resource" - 返回 resource 的responseEnd timestamp 和  startTime timestamp的时间差. 例如： entry.entryType "resource"，entry.duration 901.1400000000001, entry.responseEnd 2527.82, entry.startTime 1626.68， 2527.82 - 1626.68 == 901.1400000000001；

This property is 只读 .

Syntax

entry.duration;

Return value

A DOMHighResTimeStamp representing the duration of the performance entry. If the duration concept doesn't apply for a particular performance metric, the browser may choose to return a duration of 0.

Note: if the performance entry has an entryType of "resource" (i.e. the entry is a PerformanceResourceTiming object), this property returns the difference between the PerformanceEntry.responseEnd and PerformanceEntry.startTime timestamps.

Example

The following example shows the use of the duration 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 2 duration	Candidate Recommendation
Performance Timeline duration	Recommendation	Initial definition.

Browser compatibility

BCD tables only load in the browser

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.