Javascript function and object

1. javascript use function to define type, and use function to initialize an object. But remember javascript has no concept of Class in most object oriented languages.

2. public and private fields and function of an object

 

var MyFunc=function(title){
    this.title=title;             //public property
    var songs=new Array();        //private property
    this.addSong=function(song){  //public function
        songs.push(song);
    };
    this.getSongs=function(){
        for(var index in songs){
            alert(songs[index]);
        }
    };
    var pFunc=function(){};
};
alert(typeof(MyFunc));                //"function"
alert(typeof(MyFunc("you")));         //undefined
var obj1=new MyFunc("kaqi");
alert(typeof(obj1));                  //"object"
alert("title:"+obj1.title);           //"kaqi"
obj1.addSong("s1");
obj1.addSong("s2");
obj1.getSongs();                      //"s1" "s2"
obj1.pFunc();                         //obj1.pFunc is not a function because it is private  

 

 

3. The following three objects defined are all the same.

var oneOff={a:"a","b":"b"};
var oneObj=new Object();
oneObj.a="a";
oneObj["b"]="b";
var oneFunc=new function(){
	this.a="a";
	this.b="b";
};

 

4. A more complex version of 3 with method declared.

var oneOff={a:"a","b":"b",m:function(){console.log(this);}};
var oneObj=new Object();
oneObj.a="a";
oneObj["b"]="b";
oneObj.m=function(){console.log(this);};
var oneFunc=new function(){
	this.a="a";
	this.b="b";
	this.m=function(){console.log(this);};
};

oneOff.m();
oneObj.m();
oneFunc.m();