2.0 KiB
performance-now
Implements a function similar to performance.now (based
on process.hrtime).
Modern browsers have a window.performance object with -
among others - a now method which gives time in
milliseconds, but with sub-millisecond precision. This module offers the
same function based on the Node.js native process.hrtime
function.
Using process.hrtime means that the reported time will
be monotonically increasing, and not subject to clock-drift.
According to the High
Resolution Time specification, the number of milliseconds reported
by performance.now should be relative to the value of
performance.timing.navigationStart.
In the current version of the module (2.0) the reported time is
relative to the time the current Node process has started (inferred from
process.uptime()).
Version 1.0 reported a different time. The reported time was relative
to the time the module was loaded (i.e. the time it was first
required). If you need this functionality, version 1.0 is
still available on NPM.
Example usage
var now = require("performance-now")
var start = now()
var end = now()
console.log(start.toFixed(3)) // the number of milliseconds the current node process is running
console.log((start-end).toFixed(3)) // ~ 0.002 on my systemRunning the now function two times right after each other yields a time difference of a few microseconds. Given this overhead, I think it’s best to assume that the precision of intervals computed with this method is not higher than 10 microseconds, if you don’t know the exact overhead on your own system.
License
performance-now is released under the MIT License. Copyright (c) 2017 Braveg1rl