PerformanceResourceTiming.transferSize

This article needs a technical review. How you can help.

The transferSize read-only property represents the size (in octets) of the fetched resource. The size includes the response header fields plus the response payload body (as defined by RFC7230.

If the resource is fetched from a local cache, this property returns zero.

Syntax

resource.transferSize;

Return value

A number representing the size (in octets) of the fetched resource. The size includes the response header fields plus the response payload body (RFC7230).

Example

The following example, the value of size properties of all "resource" type events are logged.

function log_sizes(perfEntry){
  // Check for support of the PerformanceEntry.*size properties and print their values
  // if supported.
  if ("decodedBodySize" in perfEntry)
    console.log("decodedBodySize = " + perfEntry.decodedBodySize);
  else
    console.log("decodedBodySize = NOT supported");

  if ("encodedBodySize" in perfEntry)
    console.log("encodedBodySize = " + perfEntry.encodedBodySize);
  else
    console.log("encodedBodySize = NOT supported");

  if ("transferSize" in perfEntry)
    console.log("transferSize = " + perfEntry.transferSize);
  else
    console.log("transferSize = NOT supported");
}
function check_PerformanceEntries() {
  // Use getEntriesByType() to just get the "resource" events
  var p = performance.getEntriesByType("resource");
  for (var i=0; i < p.length; i++) {
    log_sizes(p[i]);
  }
}

Specifications

Specification Status Comment
Resource Timing
The definition of 'transferSize' in that specification.
Editor's Draft Initial definition.

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support. 54.0 No support No support 41 No support
Feature Android Android Webview Firefox Mobile (Gecko) Firefox OS IE Phone Opera Mobile Safari Mobile Chrome for Android
Basic support. No support 54.0 No support No support No support 41 No support 54.0

Document Tags and Contributors

 Contributors to this page: jpmedley, rolfedh, AFBarstow
 Last updated by: jpmedley,