[whatwg] Proposal for separating script downloads and execution

[timeless]

On Wed, Feb 9, 2011 at 12:08 PM, Alexandre Morgaut
<Alexandre.Morgaut at 4d.com> wrote:
> Another approach:
> The link tag is meant to support a "prefetch" value for the "rel" attribute
> asking to preemptively cache the resource:
>  - http://blog.whatwg.org/the-road-to-html-5-link-relations#rel-prefetch
>  - http://davidwalsh.name/html5-prefetch
> We can then write:
> <link rel="prefetch" type="text/javascript" src="myscript.js">
> let the link HTML Element have an execute() method when the "type" attribute
> is one off a User-Agent supported Scripting Media Types:
>
>       +-----------------------------------------------------+
>       | text/javascript          | text/ecmascript          |
>       | text/javascript1.0       | text/javascript1.1       |
>       | text/javascript1.2       | text/javascript1.3       |
>       | text/javascript1.4       | text/javascript1.5       |
>       | text/jscript             | text/livescript          |
>       | text/x-javascript        | text/x-ecmascript        |
>       | application/x-javascript | application/x-ecmascript |
>       | application/javascript   | application/ecmascript   |
>       +-----------------------------------------------------+
>
> (source: RFC 4329 "Scripting Media Types"
> - http://www.rfc-editor.org/rfc/rfc4329.txt )
> let the execute property value be null otherwise
> Note 1:
> Glenn just told me: "I doubt it's possible to change an object's interface
> based on the current value of an attribute."
> So, the execute() method may exits everytime and throw an Error like:
>  "Wrong call, the resource is not executable"
>
> Note2
> The rel attribute can accept several values.
> - http://www.whatwg.org/specs/web-apps/current-work/multipage/semantics.html#attr-link-rel
> It may then accept an additional "script" value,
> The link tag may take profit from a getElementsByRelationship(relationName)
> method similar to getElementsByClassName(className)
> This way, prefetched scripts could be more easily retrievable (as any other
> link tag)

i'm not sure you need an execute(), you might benefit from an event
listener to tell you if a resource has been prefetched. but this
general path seems less icky to me than most if not all of the other
paths suggested in this thread.