JavaScript使用享元模式实现文件上传优化操作示例

var Upload = function( uploadType ){
  this.uploadType = uploadType;
};
Upload.prototype.delFile = function( id ){
  uploadManager.setExternalState( id, this );
  if( this.fileSize < 300 ){
   return this.dom.parentNode.removeChild( this.dom );
  }
  if( window.confirm('确定要删除该文件吗？' + this.fileName )){
     return this.dom.parentNode.removeChild( this.dom);
  }
};
var UploadFactory = (function(){
  var createdFlyWeightObjs = {};
  return {
    create: function( uploadType ){
      if(createFlyWeightObjs[uploadType]){
        return createdFlyWeightObjs[uploadType];
      }
      return createdFlyWeightObjs[uploadType] = new Upload(uploadType);
    }
  }
})();
var uploadManager = (function(){
  var uploadDatabase = {};
  return{
    add: function(id, uploadType, fileName, fileSize){
      var flyWeightObj = UploadFactory.create( uploadType );
      var dom = document.createElement( 'div' );
      dom.innerHTML = '<span>文件名称：'+fileName+'，文件大小：' +fileSize + '</span>' + '<button class="delFile">删除</button>';
      dom.querySelector( ".delFile" ).onclick = function(){
       flyWeightObj.delFile( id );
       document.body.appendChild( dom );
       uploadDatabase[ id ] = {
         fileName: fileName,
         fileSize: fileSize,
         dom: dom
       };
       return flyWeightObj;
     },
     setExternalState: functon( id, flyWeightObj ){
        var uploadData = uploadDatabase[ id ];
        for( var i in uploadData){
           flyWeightObj[ i ] = uploadData[ i ];
        }
     }
  }
})();

var id = o;
window.startUpload = function( uploadType, files ){
  for( var i=0,file; file = fules[ i ++ ];){
     var uploadObj = uploadManger.add( ++id, uploadType, file.fileName, file.fileSize );
  }
};

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