javascript源对象于对象引用之前不得不说的事情

var  source = {"a":3,"b":4};//源对象


var  cpsource = source;


cpsource.c = 5;


//source.c 输出的是5



cpsource = {"c":5};


source.c //输出的是undefined


//引用对象只能对源对象进行扩展而不能进行修改