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.

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).

Examples

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
Resource Timing Level 2
# dom-performanceresourcetiming-transfersize

Browser compatibility

BCD tables only load in the browser