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The requestStart
property returns a timestamp
of the time immediately before the browser starts requesting the resource from the server, cache, or local resource. If the transport connection fails and the browser retires the request, the value returned will be the start of the retry request.
There is no end property for requestStart
.
This property is Read only .
Syntax
resource.requestStart;
Return value
A DOMHighResTimeStamp
representing the time immediately before the bowser starts requesting the resource from the server
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 The definition of 'requestStart' in that specification. |
Editor's Draft | Initial definition. |
Browser compatibility
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari (WebKit) |
---|---|---|---|---|---|
Basic support. | 43 | 40 | 10 | 32 | No support |
Feature | Android | Firefox Mobile (Gecko) | Firefox OS | IE Phone | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|---|
Basic support. | 4.4 | 42 | ? | 10.0 | 32 | No support |