PerformanceResourceTiming.fetchStart

The fetchStart read-only property represents a timestamp immediately before the browser starts to fetch the resource.

If there are HTTP redirects the property returns the time immediately before the user agent starts to fetch the final resource in the redirection.

Note: This feature is available in Web Workers.

Syntax

resource.fetchStart;

Return value

A DOMHighResTimeStamp immediately before the browser starts to fetch the resource.

Example

In the following example, the value of the *Start and *End properties of all "resource" type events are logged.

function print_PerformanceEntries() {
  // Use getEntriesByType() to just get the "resource" events
  var p = performance.getEntriesByType("resource");
  for (var i=0; i < p.length; i++) {
    print_start_and_end_properties(p[i]);
  }
}
function print_start_and_end_properties(perfEntry) {
  // Print timestamps of the PerformanceEntry *start and *end properties 
  properties = ["connectStart", "connectEnd",
                "domainLookupStart", "domainLookupEnd",
                "fetchStart", 
                "redirectStart", "redirectEnd",
                "requestStart", 
                "responseStart", "responseEnd",
                "secureConnectionStart"];

  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] + " = NOT supported");
    }
  }
}

Specifications

Specification Status Comment
Resource Timing Level 1
The definition of 'fetchStart' in that specification.
Candidate Recommendation Initial definition.

Browser compatibility

We're converting our compatibility data into a machine-readable JSON format. This compatibility table still uses the old format, because we haven't yet converted the data it contains. Find out how you can help!

Feature Chrome Edge Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support. 43 (Yes) 40 10 32 No support
Feature Android Edge Firefox Mobile (Gecko) Firefox OS IE Phone Opera Mobile Safari Mobile
Basic support. 4.4 (Yes) 42 ? 10.0 32 No support

Document Tags and Contributors

 Contributors to this page: chrisdavidmills, abbycar, rolfedh, AFBarstow
 Last updated by: chrisdavidmills,