.extend, not prototype for classes?

2018-06-09 01:17:25

I've read an interesting article on DOM prototype extension, showing some good reasons to not always rely on prototypes of Element - I didn't know there were subclasses of elements, like

HTMLParagraphElement.prototype <- HTMLElement.prototype <- Element.prototype <- Node.prototype <- Object.prototype

In general, Object prototypes can be used for subclassing, but often I see _.extend used to create mixins or base-classes, for example as seen in the Backbone source code.

_.extend(Model.prototype, Events, {...stuff...}

Why was this used instead of something like:

function innerModel() { ...stuff...}
innerModel.prototype = Events

Model.prototype = innerModel

Is the lack of prototype-chain visualization and debugging in browsers a reason _.extend is often used for subclassing instead of object's prototype?

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