Modules feedback, proposal

John J Barton johnjbarton at
Sun Apr 1 14:23:39 PDT 2012

On Sun, Apr 1, 2012 at 11:33 AM, Brendan Eich <brendan at> wrote:

> I agree with you, auto-appending is too concrete and JS-only. We can't use
> auto-append as a fallback since it's ambiguous (foo and foo.js could exist)
> and we shouldn't prefer foo based on existence (we'd have to GET twice or
> otherwise probe for existence). We want names not to depend on whether the
> URI denotes an existing "file".
> I don't agree with reinventing MIME, er, IANA Media, Types, though.

The System.load() exists at the interface between JS and the browser. JS
devs need features similar to the 'text!someCSS' and require.toUrl() to
load dependencies into JS programs using the same path system that maps
URLs to module resources.
While I understand that ES may not want to tackle this aspect, this needs
to happen in a way the devs can rely upon across browsers.

> The rules for content typing from HTML, specifically for <script src=>,
> should be adapted with as few changes as possible for out-of-line modules.

Yes, even more so if ES delegates to another group for the rest.


> /be
> John J Barton wrote:
>> On Sat, Mar 31, 2012 at 6:30 PM, David Herman <dherman at<mailto:
>> dherman at>> wrote:
>>    >
>>    > baseUrl + ID + ".js"
>>    Yeah, I've thought about auto-appending ".js". I think you're
>>    right that it opens up the possibility to be a little more abstract.
>> Auto-appending makes the API less abstract:the arguments must be JS. That
>> in turn requires some new type-signaling string to opt out of JS if you
>> want to expand the loader to other kinds of dependents. RequireJS uses a
>> type-signaling prefix, 'text!notJS' and it has different rules for things
>> that end do or do not end in  '.js'. All of this has value at the cost of
>> complexity. I'd like to see the standard file extension naming used by
>> default.
>> In the code:
>>  System.load(["jquery.js", "underscore.js"], function ($, _) {})
>> the string "jquery.js" and "underscore.js" are combined with path info to
>> create URLs. They identifies a resource, not a module; they should hew to
>> standard URL naming conventions. (The tokens $ and _ refer to modules).
>>  jjb
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