var path = require('path')
var fs  = require('fs')
//需要统计的文件类型，可自己删减，均小写
var codesFiles = [ '.css', '.js', '.html', '.tmpl', '.part', '.json', '.md', '.txt', '.yml', '.java', '.cs', '.c', '.h', '.cpp', '.xml', '.go', '.py' ]
var LINES = 0
var findFolder = function(srcDir, cb) {
 fs.readdir(srcDir, function(err, files) {
  var count = 0
  var checkEnd = function() {
   ++count == files.length && cb && cb()
  }
  if (err) {
   checkEnd()
   return
  }
  files.forEach(function(file) {
   var extname = path.extname(file).toLowerCase()
   var srcPath = path.join(srcDir, file)
   fs.stat(srcPath, function(err, stats) {
    if (stats.isDirectory()) {
     findFolder(srcPath, checkEnd)
    } else {
     if (codesFiles.indexOf(extname) < 0) {
      checkEnd()
      return
     }
     fs.readFile(srcPath, function(err, data) {
      if (err) {
       checkEnd()
       return
      }
      var lines = data.toString().split('\n')
      LINES += lines.length
      console.log(srcPath, lines.length)
      checkEnd()
     })
    }
   })
  })
  //为空时直接回调
  files.length === 0 && cb && cb()
 })
}
findFolder('./', function() {
 console.log('LINES:', LINES)
})

$ node lines.js
lines.js 56
package.json 6
local\en-US.js 122
local\FE.zh-CN.js 306
...
LINES: 40464

var path = require('path')
var fs  = require('fs')
var LINES = 0
var FILES = 0
//https://github.com/hellosean1025/study/blob/master/function.js
function isTextFile( filepath, length ) {
 fd = fs.openSync( filepath, 'r' );
 length = length || 1000;
 for( var i = 0;i < length;i++ ) {
   buf = new Buffer( 1 );
   var bytes = fs.readSync( fd, buf, 0, 1, i );
   char = buf.toString().charCodeAt();
   if ( bytes === 0) {
     return true;
   } else if(bytes === 1 && char === 0) {
     return false;
   }
 }
 return true;
}
var findFolder = function(srcDir, cb) {
 fs.readdir(srcDir, function(err, files) {
  var count = 0
  var checkEnd = function() {
   ++count == files.length && cb && cb()
  }
  if (err) {
   checkEnd()
   return
  }
  files.forEach(function(file) {
   var extname = path.extname(file).toLowerCase()
   var srcPath = path.join(srcDir, file)
   fs.stat(srcPath, function(err, stats) {
    if (stats.isDirectory()) {
     findFolder(srcPath, checkEnd)
    } else {
     // if (codesFiles.indexOf(extname) < 0) {
     //  checkEnd()
     //  return
     // }
     if (!isTextFile(srcPath)) {
      checkEnd()
      return
     }
     fs.readFile(srcPath, function(err, data) {
      if (err) {
       checkEnd()
       return
      }
      var lines = data.toString().split('\n')
      LINES += lines.length
      if (lines.length > 5000) {
       console.trace(srcPath, lines.length)       
      } else {
       console.log(srcPath, lines.length)
      }
      FILES++
      checkEnd()
     })
    }
   })
  })
  //为空时直接回调
  files.length === 0 && cb && cb()
 })
}
findFolder('./', function() {
 console.log('LINES:', LINES)
 console.log('FILES:', FILES)
})