Do line/column numbers start at 0 or 1?

[Eddy Bruel]

The debugger API allows you to get the line number of a script relative to
the source from which it was compiled (via
Debugger.Script.prototype.startLine). I'm currently working on an API that
allows you to get the line number of a source relative to the resource that
introduced it (see bug 1288084
<https://bugzilla.mozilla.org/show_bug.cgi?id=1288084>). Eventually, I
would like the same information for column numbers as well.

It's not 100% clear to me whether line/column numbers are supposed to start
at 0 or 1. I *think* line numbers are supposed to start at 1 in the JS
engine. However, I've also seen places where we use 0 for the line number.
To add to the confusion, we also seem to use 0 and 1 as default values for
when the line number is unknown. Columns numbers are similarly confusing.

I'd like to establish what the desired convention is here before I start
landing any patches in bug 1288084. Should line/column numbers start at 0
or at 1? And what should be the default value if those numbers are unknown?

[Nick Fitzgerald]

Error().stack uses 1-based lines and 1-based columns across all browsers.
We should be consistent with that.

[Jim Blandy]

I think numbering the first line of the file 1 is pretty much the standard.

On Thu, Aug 25, 2016 at 9:33 AM, Nick Fitzgerald <nfitz...@mozilla.com>
wrote:

[Tom Tromey]

>>>>> "Nick" == Nick Fitzgerald <nfitz...@mozilla.com> writes:

Nick> Error().stack uses 1-based lines and 1-based columns across all browsers.
Nick> We should be consistent with that.

What we choose for our tools is up to us, but it's worth remembering
that the browser isn't internally consistent: Error uses 1-based
columns, but the Reflect.parse AST uses 0-based columns (and this is
baked into the estree spec now). This is bound to cause confusion, so
I'd suggest comments everywhere explaining the local choices.

Tom

[Jim Blandy]

+1

[Eddy Bruel]

or is it +0?

[Mike Ratcliffe]

If I remember rightly, DOM 0 events e.g. onclick="blah()" use line 0.

On 25/08/2016 16:10, Eddy Bruel wrote:
> The debugger API allows you to get the line number of a script relative to
> the source from which it was compiled (via
> Debugger.Script.prototype.startLine). I'm currently working on an API that
> allows you to get the line number of a source relative to the resource that
> introduced it (see bug 1288084
> <https://bugzilla.mozilla.org/show_bug.cgi?id=1288084>). Eventually, I
> would like the same information for column numbers as well.
>
> It's not 100% clear to me whether line/column numbers are supposed to start
> at 0 or 1. I *think* line numbers are supposed to start at 1 in the JS
> engine. However, I've also seen places where we use 0 for the line number.
> To add to the confusion, we also seem to use 0 and 1 as default values for
> when the line number is unknown. Columns numbers are similarly confusing.
>
> I'd like to establish what the desired convention is here before I start
> landing any patches in bug 1288084. Should line/column numbers start at 0
> or at 1? And what should be the default value if those numbers are unknown?

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