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
Resource Timing Level 2 (Resource Timing 2)
# dom-performanceresourcetiming-fetchstart

Browser compatibility

BCD tables only load in the browser