durations

2019-11-10 admin

durations是什么

什么是durations,Duration tracking and formattng for node.js

durations使用教程帮助文档

durations

Build Status NPM version

Compatibilty

Both Node.js and browsers are supported by durations. When using Node.js, the nanosecond-granulatiry process.hrtime() function is used. The best substitution is selected when in the browser such that consistency is maintained even if time granularity cannot be.

Installation

npm install --save durations

Methods

The following functions are exported:

  • duration(nanoseconds) - constructs a new Duration
  • nanos(nanoseconds) - constructs a new Duration
  • micros(microseconds) - constructs a new Duration
  • millis(milliseconds) - constructs a new Duration
  • seconds(seconds) - constructs a new Duration
  • stopwatch() - constructs a new Stopwatch (stopped)
  • time(function) - times a function synchronously
  • timeAsync(function(callback)) - times a function asynchronously
  • timePromised(function()) - times a promise-returning function

Duration

Represents a duration with nanosecond granularity, and provides methods for converting to other granularities, and formatting the duration.

Methods

  • format() - human readable string representing the duration
  • nanos() - duration as nanoseconds
  • micros() - duration as microseconds
  • millis() - duration as milliseconds
  • seconds() - duration as seconds
  • minutes() - duration as minutes
  • hours() - duration as hours
  • days() - duration as days
const {duration} = require('durations')

const nanoseconds = 987654321
console.log("Duration is", duration(nanoseconds).format())

// Or, since toString() is an alias to format()
console.log(`Duration is ${duration(nanoseconds)}`)

Stopwatch

A nanosecond granularity (on Node.js) stopwatch with chainable control methods, and built-in formatting.

Stopwatch Methods

  • start() - start and return the stopwatch (no-op if already running)
  • stop() - stop and return the stopwatch (no-op if not running)
  • reset() - reset to zero elapsed time and return the stopwatch (implies stop)
  • duration() - fetch the elapsed time as a Duration
  • isRunning() - is the stopwatch running (true/false)
const {stopwatch} = require('durations')
const watch = stopwatch()

// Pauses the stopwatch. Returns the stopwatch.
watch.stop()

// Starts the stopwatch from where it was last stopped. Returns the stopwatch.
watch.start()

// Reset the stopwatch (duration is set back to zero). Returns the stopwatch.
watch.reset()

console.log(`${watch.duration().seconds()} seconds have elapsed`)
// OR
console.log(`${watch} have elapsed`)

Timer

Times the execution of a function, and returns the duration.

const {time: timeSync, timeAsync} = require('durations')

// Synchronous work
const someFunction = () => {
  let count = 0

  while (count < 1000000) {
    count++
  }

  console.log(`Count is: ${count}`)
}

console.log(`Took ${timeSync(someFunction)} to do something`)

// Asynchronous work
const someOtherFunction = next => {
  someFunction()
  next()
}

timeAsync(someOtherFunction, duration => {
  console.log(`Took ${duration} to do something else.`)
})

// Promised work
const somePromisedOp = () => {
  return new Promise((resolve) => {
    someFunction()
    resolve()
  })
}

timePromised(somePromisedOp)
.then(duration => {
  console.log(`Took ${duration} to keep promise.`)
})

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