Javascript classes vs objects, pros and cons?

Question

In my most recent javascript program (which is mostly for fun and proof-of-concept than anything else) I have a lot of different kinds of objects and of each kind I\'d have

Answer 1

In terms of performance, the difference comes when you add methods. If you use object literals each object needs to have a field for each method:

obj1--> { x: 10,
          f1: method1,
          f2: method2 }

obj2--> { x: 17,
          f1: method1,
          f2: method2 }

With classes, you can share common properties behind a shared prototype:

obj1--> { x:10,
          __proto__: --------> { f1: method1,
         }              /---->   f2: method2 }
                        |
obj2--> { x:17,         |
          __proto__: ---/
        }

That said, the performance differences are only going to matter if you instantiate a lot of objects and those objects have many methods and many of those methods are closures. If I were you I would give a greater emphasis to code style issues: for example, with the object literal method you can use closures to simulate private variables while if the methods are in a shared public prototype then all your instance variables need to be public.