[whatwg] HTML 5 drag and drop feedback

[Jens Alfke]

On Sep 3, 2009, at 6:05 PM, Francisco Tolmasky wrote:

> However, I think the addition of the deferred setData methods could  
> be added today in a way that is completely backwards compatible with  
> current implementations and would still be of great benefit.  
> Specifically, my request for deferring the calling of toString on  
> non-string objects as such:
>
> event.dataTransfer.setData("something", { toString: function()  
> { return expensiveFunctionCall(); } });
>
> This would allow me to submit patches to Firefox and WebKit that  
> would solve the current performance issues which are literally  
> blocking my ability to switch from "fake" drag and drop to "native"  
> drag and drop. At the same time, this should still work today in all  
> browsers that implement setData because the object is coerced into a  
> string immediately for you, thus not requiring immediate action on  
> their part to change anything.

+1. A real drag-n-drop API has to support promised data.

—Jens