Support for source maps

[ghost]

I don't know if this has been asked before (couldn't find anything), but it would be quite nice if, just like Chrome and other programs, Node.js would have built-in support for source maps.

Currently, there is node-source-map-support, which is quite good, but given the myriad of JavaScript dialects that are in use today and given that source maps are so widespread, I think it would be useful if was default behavior of Node itself.

Can be considered low-priority, of course.

[bnoordhuis]

Previous discussion: nodejs/node-v0.x-archive#3712

I don't think source map support is out of the question but a lot depends on whether it can be added without causing performance regressions in the module loader and elsewhere.

We can leverage v8::UnboundScript::GetSourceMappingURL() to avoid scanning the source ourselves. The problematic part is almost certainly rewriting stack traces; I speculate V8 will have to support source maps natively in order for that to perform well. Anyone who wants to take that on should file a bug or email v8-dev@ to get their input first.

[Fishrock123]

I've thought of this, but seems fine as a user module solution if that works well.

[ghost]

@Fishrock123 True; that's why I thought of it as low-priority.

[jasnell]

+1 on @bnoordhuis' comment. If this were to be done efficiently I would have to imagine it would need to be in v8 itself. /cc @nodejs/v8

[jasnell]

FYI: related: #6725 (comment)

[Trott]

This issue has been inactive for sufficiently long that it seems like perhaps it should be closed. Feel free to re-open (or leave a comment requesting that it be re-opened) if you disagree. I'm just tidying up and not acting on a super-strong opinion or anything like that.