PerformanceResourceTiming.requestStart
The requestStart
read-only 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
.
Note: This feature is available in Web Workers
Syntax
resource.requestStart;
Return value
A DOMHighResTimeStamp
representing the time immediately before the
browser 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 |
---|
Resource Timing Level 2 # dom-performanceresourcetiming-requeststart |
Browser compatibility
BCD tables only load in the browser