Re: [whatwg] Preparing <script> for ES6 modules

（我完全沒看，不過感覺是很有意思的問題，所以轉一下。最近 Hax 在
es-discuss 上貢獻也蠻多的）

(12/08/30 23:45), Jonas Sicking wrote:
> Hi All,
> 
> The current ES6 drafts have the ability to declaratively linking to
> script modules. These modules live in external resources, i.e. they
> are a separate script file. The intent is that these should be loaded
> before the script is executed and so no blocking IO is required, even
> though the syntax "looks" synchronous, i.e. doesn't have any
> asynchronous callbacks or similar.
> 
> This is very similar to how the @import rules work in CSS.
> 
> You can read more about them at
> http://calculist.org/blog/2012/03/29/synchronous-module-loading-in-es6/
> 
> This will work fine in HTML for plain <script src="..."> and <script>
> appearing in the markup. The browser simply blocks the parser until
> all dependent script modules have been loaded and then executes the
> script like normal. However it's not currently possible to do
> something like
> 
> <script defer>
> import $ from "jquery.js";
> $(...);
> </script>
> 
> or
> 
> <script async>
> import $ from "jquery.js";
> $(...);
> </script>
> 
> since the defer and async attributes are ignored for inline scripts.
> This technically works, but means that you can't take advantage of the
> performance advantages that defer and async provides, unless you also
> break out your script into an external file which cause an additional
> resource load.
> 
> We could define that async and defer only has effect on inline scripts
> if these scripts contain references to external modules. However that
> means making their behavior a lot more inconsistent and error prone.
> Especially if contents of the script element contains server-side
> generated code which may or may not include module references.
> 
> So I propose that we make defer and async consistently apply in inline
> scripts. The defer attribute used to apply to inline scripts in the
> firefox and IE implementations. It no longer does in Firefox, but I
> haven't tried in IE. However this still seems to lessen the risk of
> webcompat regressions significantly. The async attribute is new enough
> that I wouldn't be worried that there is a lot of content out there
> that would be affected by this change.
> 
> Let me know what you think.
> 
> / Jonas
> 


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Received on Thursday, 30 August 2012 19:08:54 UTC