Question

I rather like the prototype way of programming and have been trying to understand it in javascript.

I saw this bit of code in The Good Parts:

function beget(o){
  function F(){
    F.prototype = o;
  };
  return new F();
};

I don’t get this at all lol. If all you have to do is set the prototype to a past object, then couldn’t you just do this:

var parent = {
  num = 66;
};
var child = {
  prototype: parent
};

This doesn’t seem to work though, cause child.num is returned as undefined. How do you describe javascript prototype programming and what are your methods?
Thanks guys

Answer 1

You can only add prototype to a function object. When invoked via new it will use it as its prototype.

Btw, the function you quoted is part of the new version of ECMAScript as Object.create (with an additional propertiesObject parameter).

Let me put it this way: {object} is a singleton. A function() object however is a constructor, that is, when called with new creates an instance (by executing the function’s body, and using the constructor’s prototype). Of course the prototype can be a function object too, and have its own prototype, etc. Specialization and Generalization means walking up and down the prototype chain.