Things that defined by WebIDL

Question

After reading this post, http://mcc.id.au/2013/lca-webidl/

I have some questions in the page 20,

1. What happens when you pass too many/few arguments.

2. What happens when you grab a Function corresponding to an IDL operation and apply it to some other type of object.

3. How interface inheritance corresponds to a prototype chain.

4. How DOM objects are stringified.

Can anyone give a specific explanation or example to these points.

Thanks

Answer 1

1. If you pass too many arguments the extra ones are ignored. Try document.getElementsByTagName("a", "b"). If you pass too few, you get an exception: document.getElementsByTagName().
2. If you apply a WebIDL operation to the wrong type of object, you get an exception. See http://heycam.github.io/webidl/#es-operations step 4 under "Try running the following steps". document.getElementsByTagName.call(document.body, "div") for example.
3. Interface inheritance corresponds to a prototype chain as described at http://heycam.github.io/webidl/#interface-prototype-object but in brief if you have interface Foo : Bar { }; then Object.getPrototypeOf(Foo.prototype) === Bar.prototype. So for example, the prototype of HTMLElement.prototype is Element.prototype.
4. DOM objects with a stringifier defined (e.g. HTMLAnchorElement) are stringified however the relevant specification defines them to be. All other objects become "[object MostDerivedInterfaceName]".