On Mon, Jun 13, 2011 at 5:44 AM, radiate <[email protected]> wrote:
> Not sure if I misunderstood the purpose the prototype object of a
> javascript object but I wanted to add functionality to an HTML Table
> Cell that would generate a text box if a user clicked on the cell. I
> wanted to provide this functionality to all table cells in the table.
> I thought this would be a good use of the prototype functionality in
> Javascript. It seems like I can't get it to work. Here's the code:
Well, there are two reasons it's not really working or going to work like that.
For one, in order to extend an object through prototype you have to
extend the parent object's prototype property, not that of the child.
So.. if person is a child of Person:
person.prototype.newMethod = function(){}; // NOT
Person.prototype.newMethod = function(){}; // YES
Note that the .prototype property of an instance (person) does not
refer to "its prototype object", or Person.prototype. Formally you
have no access to it through an instance but in most (not all!)
browsers you can still find it through .__proto__ .
The other reason results might vary is because dom nodes are
implemented using so called "host objects". These are special kinds of
objects that typically don't adhere to the general rules of js. That
means that in most cases, they behave as regular objects insofar as
accessing properties go (and not even that, really) but extending them
or creating new instances of them is all left up to the
implementation. Pretty much any object related to the DOM is a host
object.
- peter
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