PerformanceEntry: toJSON() method
Baseline
Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since October 2017.
Note: This feature is available in Web Workers.
The toJSON() method of the PerformanceEntry interface returns a JSON-serializable plain object representing the PerformanceEntry object.
The method is automatically called by JSON.stringify() when a PerformanceEntry object is encountered during JSON serialization.
Syntax
toJSON()
Parameters
None.
Return value
A JSON-serializable plain object containing the following properties:
Each property's value is copied as-is.
Examples
Calling toJSON() directly
This example obtains a PerformanceEntry object. Calling toJSON() directly returns a plain object. Its properties have the same values as the corresponding properties of the original object.
performance.mark("debug-marker", {
detail: "debugging-marker-123",
});
const observer = new PerformanceObserver((list) => {
list.getEntries().forEach((entry) => {
const json = entry.toJSON();
console.log(json); // A plain object
console.log(typeof json); // "object"
console.log(json.name); // Same value as entry.name
});
});
observer.observe({ type: "mark", buffered: true });
Serializing to a JSON string
Within the callback from the previous example, the same object can be serialized using JSON.stringify(), which calls the toJSON() method automatically.
console.log(JSON.stringify(entry));
This would log a JSON string like so (formatted for readability):
{
"name": "debug-marker",
"entryType": "mark",
"startTime": 158361.5,
"duration": 0,
"navigationId": 2463
}
Note that it doesn't contain PerformanceMark's detail property.
Specifications
| Specification |
|---|
| Performance Timeline # dom-performanceentry-tojson |