纯异步nodejs文件夹(目录)复制功能

var async = require("async"); 
var fs = require("fs"); 
var path = require("path"); 
// cursively make dir  
function mkdirs(p, mode, f, made) { 
  if (typeof mode === 'function' || mode === undefined) { 
    f = mode; 
    mode = 0777 & (~process.umask()); 
  } 
  if (!made) 
    made = null; 
  var cb = f || function () {}; 
  if (typeof mode === 'string') 
    mode = parseInt(mode, 8); 
  p = path.resolve(p); 
  fs.mkdir(p, mode, function (er) { 
    if (!er) { 
      made = made || p; 
      return cb(null, made); 
    } 
    switch (er.code) { 
    case 'ENOENT': 
      mkdirs(path.dirname(p), mode, function (er, made) { 
        if (er) { 
          cb(er, made); 
        } else { 
          mkdirs(p, mode, cb, made); 
        } 
      }); 
      break; 
      // In the case of any other error, just see if there's a dir 
      // there already. If so, then hooray! If not, then something 
      // is borked. 
    default: 
      fs.stat(p, function (er2, stat) { 
        // if the stat fails, then that's super weird. 
        // let the original error be the failure reason. 
        if (er2 || !stat.isDirectory()) { 
          cb(er, made); 
        } else { 
          cb(null, made) 
        }; 
      }); 
      break; 
    } 
  }); 
} 
// single file copy 
function copyFile(file, toDir, cb) { 
  async.waterfall([ 
      function (callback) { 
        fs.exists(toDir, function (exists) { 
          if (exists) { 
            callback(null, false); 
          } else { 
            callback(null, true); 
          } 
        }); 
      }, function (need, callback) { 
        if (need) { 
          mkdirs(path.dirname(toDir), callback); 
        } else { 
          callback(null, true); 
        } 
      }, function (p, callback) { 
        var reads = fs.createReadStream(file); 
        var writes = fs.createWriteStream(path.join(path.dirname(toDir), path.basename(file))); 
        reads.pipe(writes); 
        /https://img.qb5200.com/download-x/don't forget close the when all the data are read 
        reads.on("end", function () { 
          writes.end(); 
          callback(null); 
        }); 
        reads.on("error", function (err) { 
          console.log("error occur in reads"); 
          callback(true, err); 
        }); 
      } 
    ], cb); 
} 
// cursively count the files that need to be copied 
function _ccoutTask(from, to, cbw) { 
  async.waterfall([ 
      function (callback) { 
        fs.stat(from, callback); 
      }, 
      function (stats, callback) { 
        if (stats.isFile()) { 
          cbw.addFile(from, to); 
          callback(null, []); 
        } else if (stats.isDirectory()) { 
          fs.readdir(from, callback); 
        } 
      }, 
      function (files, callback) { 
        if (files.length) { 
          for (var i = 0; i < files.length; i++) { 
            _ccoutTask(path.join(from, files[i]), path.join(to, files[i]), cbw.increase()); 
          } 
        } 
        callback(null); 
      } 
    ], cbw); 
} 
// wrap the callback before counting 
function ccoutTask(from, to, cb) { 
  var files = []; 
  var count = 1; 
  function wrapper(err) { 
    count--; 
    if (err || count <= 0) { 
      cb(err, files) 
    } 
  } 
  wrapper.increase = function () { 
    count++; 
    return wrapper; 
  } 
  wrapper.addFile = function (file, dir) { 
    files.push({ 
      file : file, 
      dir : dir 
    }); 
  } 
  _ccoutTask(from, to, wrapper); 
} 
function copyDir(from, to, cb) { 
  if(!cb){ 
   cb=function(){}; 
  } 
  async.waterfall([ 
      function (callback) { 
        fs.exists(from, function (exists) { 
          if (exists) { 
            callback(null, true); 
          } else { 
            console.log(from + " not exists"); 
            callback(true); 
          } 
        }); 
      }, 
      function (exists, callback) { 
        fs.stat(from, callback); 
      }, 
      function (stats, callback) { 
        if (stats.isFile()) { 
          // one file copy 
          copyFile(from, to, function (err) { 
            if (err) { 
              // break the waterfall 
              callback(true); 
            } else { 
              callback(null, []); 
            } 
          }); 
        } else if (stats.isDirectory()) { 
          ccoutTask(from, to, callback); 
        } 
      }, 
      function (files, callback) {   
        // prevent reaching to max file open limit      
        async.mapLimit(files, 10, function (f, cb) { 
          copyFile(f.file, f.dir, cb); 
        }, callback); 
      } 
    ], cb); 
} 
var start = new Date().getTime(); 
copyDir("F:\\gear", "F:\\gear2", function (err) { 
  if (err) { 
    console.log("error ocur"); 
    console.dir(err); 
  } else { 
    console.log("copy ok"); 
    console.log("consume time:" + (new Date().getTime() - start)) 
  } 
});