PerformanceResourceTiming.connectStart

The connectStart read-only property returns the timestamp immediately before the user agent starts establishing the connection to the server to retrieve the resource.

Note: This feature is available in Web Workers.

Syntax

resource.connectStart;

Return value

A DOMHighResTimeStamp immediately before the browser starts to establish the connection to the server to retrieve 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 'connectStart' in that specification.
Candidate Recommendation Initial definition.

Browser compatibility

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidEdge MobileFirefox for AndroidOpera for AndroidiOS SafariSamsung Internet
Basic supportChrome Full support 43Edge Full support 12Firefox Full support 40IE Full support 10Opera Full support 32Safari Full support 11WebView Android Full support 43Chrome Android Full support 43Edge Mobile Full support YesFirefox Android Full support 42Opera Android Full support 32Safari iOS Full support 11Samsung Internet Android Full support 4.0

Legend

Full support  
Full support

Document Tags and Contributors

Contributors to this page: ExE-Boss, fscholz, chrisdavidmills, abbycar, rolfedh, AFBarstow
Last updated by: ExE-Boss,