ctor constructor, when new an object is called-----coco2d-js, the default ctor, is the constructor of the object, others can also default other functions as constructors.
To be blunt: ctor constructor new object is automatically called, Init in cocos2d-x is the static function create () method creates the object automatically call (because the cocos2d-x provided by the macro, will be automatically called), but JS inside, need to call manually.
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The ctor constructor creates an object that differs from the method of passing the ctor function by calling Initialize init.
OnEnter is probably like this. For example, you have a reusable character sprite that addchild into the scene again without the need to call ctor creation, and you can initialize the variable character's properties in OnEnter.
COCOS2D-HTML5 OnEnter init ctor constructor----JS-specific features (a bit different from C + +)