[whatwg] Script preloading

Ryosuke Niwa rniwa at apple.com
Fri Aug 30 16:04:36 PDT 2013

On Aug 30, 2013, at 9:08 AM, Yoav Weiss <yoav at yoav.ws> wrote:

> On Tue, Aug 27, 2013 at 11:55 PM, Ian Hickson <ian at hixie.ch> wrote:
>> On Thu, 11 Jul 2013, Yoav Weiss wrote:
>>> I've recently contemplated the slightly related issue of adding the
>>> "media" attribute to <script>, for declarative loading of scripts that
>>> are only relevant to some viewports [1] While it may complicate certain
>>> things (e.g. execution when media conditions change, dependencies), I
>>> believe it's worth while to give it some thought, as it'd enable
>>> preloaders to fetch these scripts as soon as possible, in case they are
>>> needed.
>> How common are media-specific scripts?
> They are fairly common, especially for loading of "mobile" UI components
> (e.g. jquery mobile). They can also be used to download dynamic page
> components (e.g. maps) only on larger devices.
> But, unless adding `media` to script elements is relatively simple, I think
> that this use-case can be resolved by using the media attribute on <rel
> subresource>, in combination with ES6 modules or a custom script loader. As
> far as I understand it, all <link> elements can have a media attribute [1],
> so this is simply an implementation issue.

I don't think it'll be hard to add the media attribute on the script element at least in WebKit.

It'll be much harder to implement a new dependency API that replies on CSS selectors if we care about the performance at all.

- R. Niwa

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