Modules and dependencies found during the load (before instantiation)

Ian Hickson ian at
Mon Aug 18 10:55:34 PDT 2014

On Wed, 13 Aug 2014, Ian Hickson wrote:
> One of the problems I'm running into when it comes to trying to 
> integrate ES6 modules with HTML and new HTML-based dependency features 
> is the way that I can't tell ES about dependencies I know about before 
> the data is actually fetched and instantiated.

Another example of where we have something like this is HTML imports. The 
"fetch" hook for HTML imports needs to actually be the hook that does all 
the parsing, since HTML loads incrementally. (For HTML imports, the 
"translate" and "instantiate" hooks are essentially no-ops.) This means 
that the in-band dependencies for HTML imports are found during the 
"fetch" hook, and need to be set up right away. For example, if an HTML 
import contains a <script type=module> block, that inline module needs to 
be added as dependency of the import itself (so that the import's 'load' 
event doesn't fire until all internal modules are loaded). It it contains 
an <img src=""> element, that needs to be added as a dependency as its 
loading. This is similar to the "instantiate" hook adding dependencies, 
except that it has to happen earlier due to the incremental parsing.

Ian Hickson               U+1047E                )\._.,--....,'``.    fL       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'

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