Has anyone started work on a web forms 2.0 emulation library? The basic idea of the library is that the features of the incoming attributes are enforced by javascript until the browser gains the feature.

Examples:

input fields can have a required attribute, so javascript would stop form submission if a field with required has no value.

There's a new placeholder attribute that holds placeholder text that is removed onFocus and if the field is empty it is put into the field onBlur. The value of the placeholder isn't sent to the server..

And so on.