当我需要创建一个对象的副本，根据我的心情，当时，我可能使用angular.copy()或_.clone()
我发现这些方法之一可能比另一个更快，可靠/鲁棒。
另一方面，angular.extend()是一个浅拷贝类似于_.clone
Angular.copy vs Angular.extend
性能明智，我不知道哪个更好，但为了意见，我反对包括库到任何角度应用程序的全局范围(下划线)，因为通常这些东西写作angular modules. angular.copy / angular .extend在这种情况下会胜出。
浅/深复制：
Its very simple that if the object has only primitive fields,then obvIoUsly you will go for shallow copy but if the object has references to other objects,then based on the requiement,shallow copy or deep copy should be chosen. What I mean here is,if the references are not modified anytime,then there is no point in going for deep copy. You can just opt shallow copy. But if the references are modified often,then you need to go for deep copy. Again there is no hard and fast rule,it all depends on the requirement.
