返回函数的JavaScript函数

var aessors = {
 sortable: {
 get: function() {
  return typeof this.getAttribute('sortable') != 'undefined';
 }
 },
 droppable: {
 get: function() {
  return typeof this.getAttribute('droppable') != 'undefined';
 }
 }
};

function getAttribute(attr) {
 return typeof this.getAttribute(attr) != 'undefined';
}

var aessors = {
 sortable: {
 get: function() {
  return getAttribute('sortable');
 }
 },
 droppable: {
 get: function() {
  return getAttribute('droppable');
 }
 }
};

function generateGetMethod(attr) {
 return function() {
 return typeof this.getAttribute(attr) != 'undefined';
 };
}

var aessors = {
 sortable: {
 get: generateGetMethod('sortable')
 },
 droppable: {
 get: generateGetMethod('droppable')
 }
};

/ 它跟最初的方法是完全等效的/

var aessors = {
 sortable: {
 get: function() {
  return typeof this.getAttribute('sortable') != 'undefined';
 }
 },
 droppable: {
 get: function() {
  return typeof this.getAttribute('droppable') != 'undefined';
 }
 }
};

/