PerformanceNodeTiming

class PerformanceNodeTiming extends PerformanceEntry

This property is an extension by Node.js. It is not available in Web browsers.

Provides timing details for Node.js itself. The constructor of this class is not exposed to users.

The high resolution millisecond timestamp at which the Node.js process completed bootstrapping. If bootstrapping has not yet finished, the property has the value of -1.

The high resolution millisecond timestamp at which the Node.js environment was initialized.

The high resolution millisecond timestamp of the amount of time the event loop has been idle within the event loop's event provider (e.g. epoll_wait). This does not take CPU usage into consideration. If the event loop has not yet started (e.g., in the first tick of the main script), the property has the value of 0.

The high resolution millisecond timestamp at which the Node.js event loop exited. If the event loop has not yet exited, the property has the value of -1. It can only have a value of not -1 in a handler of the 'exit' event.

The high resolution millisecond timestamp at which the Node.js event loop started. If the event loop has not yet started (e.g., in the first tick of the main script), the property has the value of -1.

The high resolution millisecond timestamp at which the Node.js process was initialized.

This is a wrapper to the uv_metrics_info function. It returns the current set of event loop metrics.

The values are exact up to Number.MAX_SAFE_INTEGER. Use performanceNodeTiming.uvMetricsInfoBigInt to obtain the full 64-bit values reported by libuv.

It is recommended to use this property inside a function whose execution was scheduled using setImmediate to avoid collecting metrics before finishing all operations scheduled during the current loop iteration.

const { performance } = require('node:perf_hooks');

setImmediate(() => {
  console.log(performance.nodeTiming.uvMetricsInfo);
});

import { performance } from 'node:perf_hooks';

setImmediate(() => {
  console.log(performance.nodeTiming.uvMetricsInfo);
});

The same as performanceNodeTiming.uvMetricsInfo, except that the values are bigints carrying the full 64-bit range reported by libuv.

Because JSON.stringify() cannot serialize bigint values, this property is not enumerable and is not included in the output of performanceNodeTiming.toJSON(). Copies of performance.nodeTiming made by spreading its enumerable properties, for example, remain serializable.

const { performance } = require('node:perf_hooks');

setImmediate(() => {
  console.log(performance.nodeTiming.uvMetricsInfoBigInt);
});

import { performance } from 'node:perf_hooks';

setImmediate(() => {
  console.log(performance.nodeTiming.uvMetricsInfoBigInt);
});

The high resolution millisecond timestamp at which the V8 platform was initialized.