From:  "Fitzgerald, Nick" <>
Date:  07 May 2013 06:24:28 Hong Kong Time

Re: Dynamic sourcemaps


Sorry for the delayed response, I have been on vacation. Replies inline.

On 5/3/13 8:28 AM, Thaddee Tyl wrote:
> I dug into the state of dynamic sourcemaps again today. I am unsure
> about what the acknowledged progress of it is. However, there are two
> points I would like to make on both Firefox' and Chrome's
> implementations.
> I should note that in both cases, I used the bleeding edge, that is,
> Canary and Nightly.
> Firstly, the following URL is that of a webpage which attempts to use
> dynamic sourcemaps:
> The source is URL-encoded in the JSON source map, which is itself
> encoded in a data URL. It makes use of the sources / sourcesContent
> trick.
> It simply does not work in Chrome: the source goes undetected.
> Firefox notices the source, but never loads its content, showing
> "Loading..." in the editor instead.
> In both cases, I'd love to know what is going on.

While the mozilla/source-map library supports sourcesContent, it isn't 
used in the debugger yet. See

> Which leads me to my second point. I clearly have the intention to use
> sourcemaps (it is quite easy to detect), yet no error shows up,
> neither in Firefox, nor in Chrome. Even if not spec'ed, some errors
> should show up in the developer tools, if only for library /
> transpiler authors, but also for the general developing public: if the
> sourcemap generator fails, the developer should know why, to be able
> to report the error to the transpiler author.

If you open the error console, you will see two error messages stating 
that the source could not be loaded. Agreed that this is not the best 
UX, but we are straying from the point of this list: to discuss the 
source map *specification*.

I think these concerns are better suited to

(I'm not sure what the corresponding list for Chrome is.)