Object.prototype.namespace= function(name){

     var parts = name.split('.');

     var current = this;

     for (var i in parts) {

         if(!current[parts[i]]){

             current[parts[i]]={};

         }

         current=current[parts[i]];

     };

 };

var MyApp={};

MyApp.namespace('event');

MyApp.namespace('dom.style');

// 以上代码等价于

var MyApp={

    event: {},

    dom: {

        style: {}

    }

}