Web/API/PerformanceResourceTiming/transferSize

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).

Note: This feature is available in Web Workers.

If the resource is fetched from a local cache, or if it is a cross-origin resource, 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 Level 2The definition of 'transferSize' in that specification.	Working Draft	Initial definition.

Browser compatibility

The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
transferSize	Chrome Full support 54	Edge Full support 17	Firefox Full support 45	IE No support No	Opera Full support 41	Safari No support No	WebView Android Full support 54	Chrome Android Full support 54	Firefox Android Full support 45	Opera Android Full support 41	Safari iOS No support No	Samsung Internet Android Full support 6.0

Legend

Full support  

Full support

No support  

No support

PerformanceResourceTiming.transferSize by Mozilla Contributors is licensed under CC-BY-SA 2.5.