PerformanceResourceTiming.fetchStart
The fetchStart
read-only property represents a
timestamp
immediately before the browser starts to
fetch the resource.
If there are HTTP redirects the property returns the time immediately before the user agent starts to fetch the final resource in the redirection.
Note: This feature is available in Web Workers
Syntax
resource.fetchStart;
Return value
A DOMHighResTimeStamp
immediately before the browser starts to fetch the
resource.
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-fetchstart |
Browser compatibility
BCD tables only load in the browser