什么是nanotiming，Small timing library
Small timing library. Useful to integrate into libraries that have multiple methods. Works both in the browser and Node. To use this in Node, make sure you are using v8.5.0 or greater.
var nanotiming = require('nanotiming') // require 'perf_hooks' for Node environment // var performance = require('perf_hooks').performance var timing = nanotiming('my-loop') // Start profiling var i = 1000 while (--i) console.log(i) // Stop profiling timing() // in the browser var timings = window.performance.getEntries() var timing = timings[timings.length - 1] console.log(timing.name, timing.duration) // log the last entry window.performance.clearMeasures(timing.name) // be a good citizen and free after use // in Node var timings = performance.getEntries() var timing = timings[timings.length - 1] console.log(timing.name, timing.duration) // log the last entry performance.clearMeasures(timing.name) // be a good citizen and free after use
Timings inside the view are appended with a unique UUID so they can be cleared individually. While there’s no strict format for timing formats, we recommend using a format along these lines:
choo.render  choo.route('/')  choo.emit('log:debug') 
Performance timers are still a somewhat experimental technology. While they’re a great idea conceptually, there might be bugs. To disable timings complete, in the browser set:
window.localStorage.DISABLE_NANOTIMING = true
Alternatively, in Node set:
process.env.DISABLE_NANOTIMING = true
endTiming = nanotiming(name)
Start a new timing.
The unique ID created for the timing.
Close the timing. Measuring the timing is done inside a
requestIdleCallback() (browser) or
setTimeout (node) tick, so it might not be available immediately. If a callback is passed it will be called with an error (if measuring wasn’t successful) and the timing’s name.