Javascript UndoManager Browser Support

The HTML5 spec mentions an UndoManager that can be used to query the previous state 开发者_如何学运维of a document that's been edited by a user ( http://www.whatwg.org/specs/web-apps/current-work/#undomanager ). Do any browsers support this? Is there any hope of browsers ever supporting it?

You can test your own browsers by navigating them to HTML5Test.com. You can also test for it on your page (and then use it if it exists) by doing the following:

return typeof UndoManager !== 'undefined';

The browsers that currently support it are limited.

No Support: Chrome 6.0, IE 8, FF 3.6

Browser       Score (160)   UndoManager Support
--------------------------------------
IE8           19            no
FF3.6         101           no
Chrome 6      142           no
Safari 4.0.5  70            no
Opera 10.53   102           no

Chrome, Firefox, and Opera score well on overall HTML5 support. So, UndoManager support may be coming soon. Safari has promised full HTML5 support "soon", as well. IE9 is supposed to be more focused on web standards.

So, it doesn't look right at this moment, but I imagine there will be 3-4 major browsers with support in the near future.