yarn add benchmark --save
# 或者
npm i benchmark --save

const Benchmark = require('benchmark')
const suite = new Benchmark.Suite()
// 添加測(cè)試
suite
  /**
   * add() 方法接受兩個(gè)參數(shù)，其中第一個(gè)表示測(cè)試的名稱，第二個(gè)表示測(cè)試的內(nèi)容，他是一個(gè)函數(shù)*   
/
  .add('join1000', () => {
    new Array(1000).join(' ')
  })
  .add('join10000', () => {
    new Array(10000).join(' ')
  })
  // 添加時(shí)間監(jiān)聽(tīng)
  .on('cycle', event => {
    // 打印執(zhí)行時(shí)間
    console.log(String(event.target))
  })
  // 完成后執(zhí)行觸發(fā)的事件
  .on('complete', () => {
    console.log('最快的是：' + suite.filter('fastest').map('name'))
  })
  // 執(zhí)行測(cè)試
  .run({ async: true })

復(fù)制代碼

...
suite
  .add('全局變量', () => {
    // 該函數(shù)內(nèi)模擬全局作用域
    let i,
      str = ''
    for (i = 0; i < 1000; i++) {
      str += i
    }
  })
  .add('局部變量', () => {
    for (let i = 0, str = ''; i < 1000; i++) {
      str += i
    }
  })
...

...
suite
  .add('構(gòu)造函數(shù)內(nèi)部添加', () => {
    function Person() {
      this.sayMe = function () {
        return '一碗周'
      }
    }
    let p = new Person()
  })
  .add('原型方式內(nèi)部添加', () => {
    function Person() {}
    Person.prototype.sayMe = function () {
      return '一碗周'
    }
    let p = new Person()
  })
...

...
suite
  .add('使用屬性訪問(wèn)方法', () => {
    function Person() {
      this.name = '一碗周'
      this.getName = function () {
        return '一碗周'
      }
    }
    let p = new Person()
    let n = p.getName()
  })
  .add('不使用屬性訪問(wèn)方法', () => {
    function Person() {
      this.name = '一碗周'
    }
    let p = new Person()
    let n = p.name
  })
...

...
suite
  .add('正序', () => {
    let arr = new Array(100)
    let str = ''
    for (let i = 0; i < arr.length; i++) {
      str += i
    }
  })
  .add('緩存', () => {
    let arr = new Array(100)
    let str = ''
    for (let i = arr.length; i; i--) {
      str += i
    }
  })
  .add('緩存的另一種寫(xiě)法', () => {
    let arr = new Array(100)
    let str = ''
    for (let i = 0, l = arr.length; i < l; i++) {
      str += i
    }
  })
...

...
suite
  .add('forEach', () => {
    let arr = new Array(100)
    let str = ''
    arr.forEach(i => {
      str += i
    })
  })
  .add('for...in', () => {
    let arr = new Array(100)
    let str = ''
    for (i in arr) {
      str += i
    }
  })
  .add('for', () => {
    let arr = new Array(100)
    let str = ''
    for (let i = 0, l = arr.length; i < l; i++) {
      str += i
    }
  })
...

...
/*** 
 接收兩類文件，zip 和 rar* 
 壓縮包的大小限制為 10 兆* 
/

suite
  .add('嵌套寫(xiě)法', () => {
    function uploadFile(suffix, size) {
      // 允許上傳的后綴名
      const suffixList = ['.zip', '.rar']
      const M = 1024*  1024

      if (suffixList.includes(suffix)) {
        if (size <= 10*  M) {
          return '下載成功'
        }
      }
    }
    uploadFile('.zip', 1*  1024*  1024)
  })
  .add('減少判斷寫(xiě)法', () => {
    function uploadFile(suffix, size) {
      // 允許上傳的后綴名
      const suffixList = ['.zip', '.rar']
      const M = 1024*  1024
      if (!suffixList.includes(suffix)) return
      if (size > 10*  M) return
      return '下載成功'
    }
    uploadFile('.zip', 1*  1024*  1024)
  })
...

...
suite
  .add('before', () => {
    var name = '一碗粥'
    function sayMe() {
      name = '一碗周'
      function print() {
        var age = 18
        return name + age
      }
      print()
    }
    sayMe()
  })
  .add('after', () => {
    var name = '一碗粥'
    function sayMe() {
      var name = '一碗周' // 形成局部作用域
      function print() {
        var age = 18
        return name + age
      }
      print()
    }
    sayMe()
  })
...

...
var userList = {
  one: {
    name: '一碗周',
    age: 18,
  },
  two: {
    name: '一碗粥',
    age: 18,
  },
}
suite
  .add('before', () => {
    function returnOneInfo() {
      userList.one.info = userList.one.name + userList.one.age
    }
    returnOneInfo()
  })
  .add('after', () => {
    function returnOneInfo() {
      let one = userList.one
      one.info = one.name + one.age
    }
    returnOneInfo()
  })
...

...
suite
  .add('before', () => {
    var str = new String('string')
  })
  .add('after', () => {
    var str = 'string'
  })
...