Javascript類比c#方法重載

每次看John Resig的blog，都會有很大的收穫！這次和大家一起分享一個Javascript類比c#方法重載的例子。

 function loadMethod(object, name, fn){ 
            var old = object[ name ]; 
            if ( old ) 
                object[ name ] = function(){ 
                    if ( fn.length == arguments.length ) 
                        return fn.apply( this, arguments ); 
                    else if ( typeof old == 'function' ) 
                        return old.apply( this, arguments ); 
                }; 
            else 
                object[ name ] = fn; 
        }

下面寫一個在使用者集合中尋找特定使用者數量的例子function UserCount(){ 
            loadMethod(this, "find", function(list){ 
                //尋找所有數量
                var i=0;
                return list.length;
            }); 
            loadMethod(this, "find", function(list,pwd){ 
                //尋找特定密碼的使用者數量
                var k=0;
                for(var i=0;i<list.length;i++)
                {
                    if(list[i].pwd==pwd)
                        k++;
                }
                return k;
            }); 
            loadMethod(this, "find", function(list,id, pwd){
                //尋找特定密碼和id的使用者數量 
                var k=0;
                for(var i=0;i<list.length;i++)
                {
                    if(list[i].id==id && list[i].pwd==pwd)
                        k++;
                }
                return k;
            })
        }

//定義集合
        var userlist=new Array();
        userlist.push({id:"holygrace",pwd:"12345"});
        userlist.push({id:"JiangYuYang",pwd:"2233"});
        userlist.push({id:"liyanhong",pwd:"12345"});
        userlist.push({id:"mayun",pwd:"adf"});
        userlist.push({id:"wangzidong",pwd:"3456"});
        
        var count=new UserCount()
        alert("find(userlist)找到\n"+count.find(userlist)+"位");
        alert("find(userlist,\"12345\")找到\n"+count.find(userlist,"12345")+"位");
        alert("find(userlist,\"holygrace\",\"12345\")找到\n"+count.find(userlist,"holygrace","12345")+"位");