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.
注意： 此特征可用于 Web 工作者 .resource.fetchStart;
A
DOMHighResTimeStamp
immediately before the browser starts to fetch the resource.
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");
}
}
}
| 规范 | 状态 | 注释 |
|---|---|---|
|
Resource Timing Level 1
The definition of 'fetchStart' in that specification. |
候选推荐 | 初始定义。 |
| 桌面 | 移动 | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
fetchStart
|
Chrome 43 | Edge 12 | Firefox 40 | IE No | Opera 30 | Safari 11 | WebView Android 43 | Chrome Android 43 | Firefox Android 42 | Opera Android 30 | Safari iOS 11 | Samsung Internet Android 4.0 |
完整支持
不支持
PerformanceResourceTiming