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Javascript ÃæÏò¶ÔÏó»úÖƵÄʵÏÖ
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function Player(url){
    this.url = url;
   
    this.showUrl = function(){
        alert(this.url);
    }
   
    this.play = function(){
        // do play
    }
}
var myPlayer = new Player("test.mp3");
myPlayer.showUrl();
alert(myPlayer instanceof Player);
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function Player(url){
   this.url = url;
   if(typeof Player._initialized == "undefined"){
      Player.prototype.showUrl = function(){
         alert(this.url);
         Player._initialized = true;
      }
   }
}
var myPlayer = new Player("test.mp3");
myPlayer.showUrl();
alert(myPlayer instanceof Player);
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JavaScript ±¾Éí²¢Ã»·¨Çø·Ö˽ÓбäÁ¿ºÍ¹«¹²±äÁ¿£¬Í¨³£ÔÚÃüÃûÉÏÇø·Öһϣ¬Ò»°ãÏ°¹ßÔÚ˽ÓбäÁ¿µÄÇ°¼ÓÒ»¸öÏ»®Ïß this._privateProperty¡£
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function Player(url){
   this.url = url;
   var self = this;
   var position;
   this.onPositionChange = null; // ʼþ¶¨Òå
   this.setPosition = function(value){
      self.position = value;
      if (this.onPositionChange)
         this.onPositionChange(this); //ʼþ´¥·¢
   }
}
   var myPlayer = new Player("test.mp3");
   myPlayer.onPositionChange = function fun(obj){ //ʼþ¶©ÔÄ
   alert(obj.position + 's Position Change');
}
myPlayer.setPosition(100);
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