PerformanceServerTiming: toJSON() method
The toJSON()
method of the PerformanceServerTiming
interface is a serializer; it returns a JSON representation of the PerformanceServerTiming
object.
Syntax
js
toJSON()
Parameters
None.
Return value
A JSON
object that is the serialization of the PerformanceServerTiming
object.
Examples
Logging server timing entries
Server timing metrics require the server to send the Server-Timing
header. For example:
http
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.
js
const observer = new PerformanceObserver((list) => {
list.getEntries().forEach((entry) => {
entry.serverTiming.forEach((serverEntry) => {
console.log(serverEntry.toJSON());
});
});
});
["navigation", "resource"].forEach((type) =>
observer.observe({ type, buffered: true })
);
This would log a JSON object like so:
json
{
"name": "cache",
"duration": 23.2,
"description": "Cache Read"
}
To get a JSON string, you can use JSON.stringify(serverEntry)
directly; it will call toJSON()
automatically.
Specifications
Specification |
---|
Server Timing # dom-performanceservertiming-tojson |
Browser compatibility
BCD tables only load in the browser