web api instance property
PerformanceServerTiming: duration property
Available in workers
The duration read-only property returns a double that contains the server-specified metric duration (usually in milliseconds), or the value 0.0.
Value
A number.
Examples
Logging server timing entries
Server timing metrics require the server to send the Server-Timing header. For example:
Server-Timing: cache;desc="Cache Read";dur=23.2
The serverTiming entries can live on navigation and resource entries.
Example using a PerformanceObserver, which notifies of new navigation and resource performance entries as they are recorded in the browser’s performance timeline. Use the buffered option to access entries from before the observer creation.
const observer = new PerformanceObserver((list) => {
list.getEntries().forEach((entry) => {
entry.serverTiming.forEach((serverEntry) => {
console.log(
`${serverEntry.name} (${serverEntry.description}) duration: ${serverEntry.duration}`,
);
// Logs "cache (Cache Read) duration: 23.2"
});
});
});
["navigation", "resource"].forEach((type) =>
observer.observe({ type, buffered: true }),
);
Example using getEntriesByType(), which only shows navigation and resource performance entries present in the browser’s performance timeline at the time you call this method:
for (const entryType of ["navigation", "resource"]) {
for (const { name: url, serverTiming } of performance.getEntriesByType(
entryType,
)) {
if (serverTiming) {
for (const { name, description, duration } of serverTiming) {
console.log(`${name} (${description}) duration: ${duration}`);
// Logs "cache (Cache Read) duration: 23.2"
}
}
}
}