<div class="alert alert-warning"><div><svg xmlns="http://www.w3.org/2000/svg" width="14" height="14" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"> <path stroke="none" d="M0 0h24v24H0z" fill="none" /> <path d="M12 9v4" /> <path d="M10.363 3.591l-8.106 13.534a1.914 1.914 0 0 0 1.636 2.871h16.214a1.914 1.914 0 0 0 1.636 -2.87l-8.106 -13.536a1.914 1.914 0 0 0 -3.274 0z" /> <path d="M12 16h.01" /> </svg> Deno compatibility</div><div><p> This symbol is not implemented.</p> </div></div>

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

Creates an IntervalHistogram object that samples and reports the event loop delay over time. The delays will be reported in nanoseconds.

Using a timer to detect approximate event loop delay works because the execution of timers is tied specifically to the lifecycle of the libuv event loop. That is, a delay in the loop will cause a delay in the execution of the timer, and those delays are specifically what this API is intended to detect.

import { monitorEventLoopDelay } from 'node:perf_hooks';
const h = monitorEventLoopDelay({ resolution: 20 });
h.enable();
// Do something.
h.disable();
console.log(h.min);
console.log(h.max);
console.log(h.mean);
console.log(h.stddev);
console.log(h.percentiles);
console.log(h.percentile(50));
console.log(h.percentile(99));