dom / latest / performancenavigationtiming / unloadeventstart.html /

PerformanceNavigationTiming.unloadEventStart

Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The unloadEventStart read-only property returns a timestamp representing the time value equal to the time immediately before the user agent starts the unload event of the previous document. If there is no previous document, this property returns 0.

Value

A timestamp representing the time value equal to the time immediately before the user agent starts the unload event of the previous document.

Examples

The following example illustrates this property's usage.

function print_nav_timing_data() {
  // Use getEntriesByType() to just get the "navigation" events
  var perfEntries = performance.getEntriesByType("navigation");

  for (var i=0; i < perfEntries.length; i++) {
    console.log("= Navigation entry[" + i + "]");
    var p = perfEntries[i];
    // dom Properties
    console.log("DOM content loaded = " + (p.domContentLoadedEventEnd - p.domContentLoadedEventStart));
    console.log("DOM complete = " + p.domComplete);
    console.log("DOM interactive = " + p.interactive);

    // document load and unload time
    console.log("document load = " + (p.loadEventEnd - p.loadEventStart));
    console.log("document unload = " + (p.unloadEventEnd - p.unloadEventStart));

    // other properties
    console.log("type = " + p.type);
    console.log("redirectCount = " + p.redirectCount);
  }
}

Specifications

Browser compatibility

Desktop Mobile
Chrome Edge Firefox Internet Explorer Opera Safari WebView Android Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet
unloadEventStart
57
12
58
11
44
15
57
57
58
43
15.1
7.0

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https://developer.mozilla.org/en-US/docs/Web/API/PerformanceNavigationTiming/unloadEventStart