1277780 - display source map variable names in Developer Tools

Status: RESOLVED DUPLICATE of bug 856875

(DevTools :: Debugger, defect, P5)

Description

[burashka-lcme]

Attachment: forFF.zip

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:46.0) Gecko/20100101 Firefox/46.0
Build ID: 2016042500

Steps to reproduce:

1) Open HTML-file with minified JavaScript.
2) Debug minified JavaScript.



Actual results:

Minified variable names are shown (ex: `a`, `c`, `e`, etc) instead of original source names.


Expected results:

Shown original source names.

Comment 1

[Eddy Bruel [:ejpbruel]]

James, didn't we already have a bug for this?

If not, this seems like it would be of some importance, so tentatively marking as P2.

Comment 2

[James Long (:jlongster)]

(In reply to Eddy Bruel [:ejpbruel] from comment #1)
> James, didn't we already have a bug for this?
> 
> If not, this seems like it would be of some importance, so tentatively
> marking as P2.

Source maps don't even have this feature, I don't think. You must be thinking of a different bug. Sourcemaps do not encode and scoping information or names of original variables, so I think this bug is invalid.

Comment 3

[James Long (:jlongster)]

Confirmed with fitzgen that the sourcemaps specification is not capable of this.

Comment 4

[burashka-lcme]

It's not impossible. Chrome DevTools implemented it: https://bugs.chromium.org/p/chromium/issues/detail?id=327092. In experimental functionality, but stability works.

Comment 5

[James Long (:jlongster)]

It's hard to tell what they are doing, but it looks like they are manually trying to re-sourcemap variable names by finding the definition location and sourcemapping that expression? We would rather improve the sourcemap spec. This isn't something we're going to do now.

Comment 6

[Tom Tromey :tromey]

I discovered that this is a dup.