var Upload = function(uploadType) {
  this.uploadType = uploadType;
}

/* 刪除文件（內(nèi)部狀態(tài)） */
Upload.prototype.delFile = function(id) {
  uploadManger.setExternalState(id, this);  // 把當(dāng)前id對(duì)應(yīng)的外部狀態(tài)都組裝到共享對(duì)象中
  // 大于3000k提示
  if(this.fileSize < 3000) {
    return this.dom.parentNode.removeChild(this.dom);
  }
  if(window.confirm("確定要?jiǎng)h除文件嗎？" + this.fileName)) {
    return this.dom.parentNode.removeChild(this.dom);
  }
}

/** 工廠對(duì)象實(shí)例化 
 * 如果某種內(nèi)部狀態(tài)的共享對(duì)象已經(jīng)被創(chuàng)建過，那么直接返回這個(gè)對(duì)象
 * 否則，創(chuàng)建一個(gè)新的對(duì)象
 */
var UploadFactory = (function() {
  var createdFlyWeightObjs = {};
  return {
    create: function(uploadType) {
      if(createdFlyWeightObjs[uploadType]) {
        return createdFlyWeightObjs[uploadType];
      }
      return createdFlyWeightObjs[uploadType] = new Upload(uploadType);
    }
  };
})();

/* 管理器封裝外部狀態(tài) */
var uploadManger = (function() {
  var uploadDatabase = {};

  return {
    add: function(id, uploadType, fileName, fileSize) {
      var flyWeightObj = UploadFactory.create(uploadType);
      var dom = document.createElement('div');
      dom.innerHTML = "<span>文件名稱：" + fileName + "，文件大?。? + fileSize +"</span>"
             + "<button class='delFile'>刪除</button>";

      dom.querySelector(".delFile").onclick = function() {
        flyWeightObj.delFile(id);
      };
      document.body.appendChild(dom);

      uploadDatabase[id] = {
        fileName: fileName,
        fileSize: fileSize,
        dom: dom
      };

      return flyWeightObj;
    },
    setExternalState: function(id, flyWeightObj) {
      var uploadData = uploadDatabase[id];
      for(var i in uploadData) {
        // 直接改變形參（新思路?。。?
        flyWeightObj[i] = uploadData[i];
      }
    }
  };
})();

/*觸發(fā)上傳動(dòng)作*/
var id = 0;
window.startUpload = function(uploadType, files) {
  for(var i=0,file; file = files[i++];) {
    var uploadObj = uploadManger.add(++id, uploadType, file.fileName, file.fileSize);
  }
};

/* 測試 */
startUpload("plugin", [
  {
    fileName: '1.txt',
    fileSize: 1000
  },{
    fileName: '2.txt',
    fileSize: 3000
  },{
    fileName: '3.txt',
    fileSize: 5000
  }
]);
startUpload("flash", [
  {
    fileName: '4.txt',
    fileSize: 1000
  },{
    fileName: '5.txt',
    fileSize: 3000
  },{
    fileName: '6.txt',
    fileSize: 5000
  }
]);

function f1() {
  var obj = {a: 1};
  f2(obj);
  console.log(obj);  // {a: 1, b: 2}
}
function f2(obj) {
  obj.b = 2;
}
f1();  

var objectPoolFactory = function(createObjFn) {
  var objectPool = [];
  return {
    create: function() {
      var obj = objectPool.lenght === 0 ? createObjFn.apply(this, arguments) : objectPool.shift();
      return obj;
    },
    recover: function() {
      objectPool.push(obj);
    }
  };
}