text: const fs = require('fs')
  const path = require('path')
  const readline = require('readline')
  
  // 文件名
  const fileName = path.join(__dirname, '../', '../', 'logs', 'access.log')
  // 创建 read stream
  const readStream = fs.createReadStream(fileName)
  
  // 创建 readline 对象
  const rl = readline.createInterface({
      input: readStream
  })
  
  let chromeNum = 0
  let sum = 0
  
  // 逐行读取
  rl.on('line', (lineData) => {
      if (!lineData) {
          return
      }
  
      // 记录总行数
      sum++
  
      const arr = lineData.split(' -- ')
      if (arr[2] && arr[2].indexOf('Chrome') > 0) {
          // 累加 chrome 的数量
          chromeNum++
      }
  })
  // 监听读取完成a
  rl.on('close', () => {
      console.log('chrome 占比：' + chromeNum / sum)
  })
  
  