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---
title: "PerformanceEntry: toJSON() method"
short-title: toJSON()
slug: Web/API/PerformanceEntry/toJSON
page-type: web-api-instance-method
browser-compat: api.PerformanceEntry.toJSON
---
{{APIRef("Performance API")}}
The **`toJSON()`** method is a {{Glossary("Serialization","serializer")}}; it returns a JSON representation of the {{domxref("PerformanceEntry")}} object.
## Syntax
```js-nolint
toJSON()
```
### Parameters
None.
### Return value
A {{jsxref("JSON")}} object that is the serialization of the {{domxref("PerformanceEntry")}} object.
## Examples
### Using the toJSON method
In this example, calling `entry.toJSON()` returns a JSON representation of the {{domxref("PerformanceMark")}} object.
```js
performance.mark("debug-marker", {
detail: "debugging-marker-123",
});
const observer = new PerformanceObserver((list) => {
list.getEntries().forEach((entry) => {
console.log(entry.toJSON());
});
});
observer.observe({ entryTypes: ["mark"] });
```
This would log a JSON object like so:
```json
{
"name": "debug-marker",
"entryType": "mark",
"startTime": 158361,
"duration": 0
}
```
Note that it doesn't contain `PerformanceMark`'s {{domxref("PerformanceMark.detail", "detail")}} property.
To get a JSON string, you can use [`JSON.stringify(entry)`](/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/stringify) directly; it will call `toJSON()` automatically.
## Specifications
{{Specifications}}
## Browser compatibility
{{Compat}}
## See also
- {{jsxref("JSON")}}