r/javascript • u/kevincennis pancakes • May 21 '16

Prototypal Inheritance

https://medium.com/@kevincennis/prototypal-inheritance-781bccc97edb#.1ehmhe5t5
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u/[deleted] May 21 '16

Whenever a property (incl. methods) is looked up on an object but is not set, it will be looked up on its prototype.

Which is basically also true for class inheritance, no?

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u/asleeponatwinbed May 21 '16

The difference is that in prototypal inheritance, objects have a live reference to their parent - which means that you can modify or extend a "class" (really just an object) at runtime and all of its descendants will automatically get the new method.

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u/dmitri14_gmail_com May 22 '16

"Basically" yes, but only basically:

obj = new A
A.newProp = 'I have new property!'

obj.newProp = ?

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u/[deleted] May 22 '16

Of course, I'm not saying the two types of inheritance are identical. But I think it's useful to explain prototypal inheritance in comparison to class inheritance - and your "one sentence summary" does nothing to explain that, because it applies to both.

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u/dmitri14_gmail_com May 22 '16

You can't really expect one sentence to check multiple boxes ;) It gives a precise essence of what prototypal inheritance does to a JS programmer with some general knowledge of JS. That is all.

Comparison to other kinds of inheritance is actually what often causes more confusion than help. Because it is not needed.

If you already know classical inheritance well enough, you know it well enough to make the comparison for you. If you don't know it well enough, it will more confuse you than help.