Json buffers don't seem to respect (set-variable 'tab-width 2)
reddit / emacs

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TomSwirly · 2022-11-10 12:36

Long-time emacs user here.

I need to occasionally edit Jason buffers indented with 2 spaces, when
my default indentation is 4.

However, incanting `(set-variable 'tab-width 2)` in such a JSON buffer
has, to my surprise, no effect.

`M-x describe-variable` says:

    tab-width is a variable defined in ‘C source code’.
    Its value is 2
    Original value was 8
    Local in buffer summary-fields.json; global value is 4

exactly as expected, but hitting tab, or even comma :-/ consistently
aligns me with 4 space tabs, which is getting me down.

`C-h m` gives me the mode:

    JavaScript mode defined in ‘js.el’:
    Major mode for editing JavaScript.

which also seems as expected.

I'm running Aquamacs 3.6  GNU Emacs 25.3.50.1

Thanks for any ideas or tips.

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globalcandyamnesia · 2022-11-10 15:47

Ugh tab size variables are so inconsistent in Emacs. I believe what
you're looking for is `js-indent-level`, but for any given mode it can
be MODE-indent-offset, MODE-basic-indent, MODE-basic-offset or who
knows what else.

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Alan_Shutko · 2022-11-10 15:49

You want to set `js-indent-level`. `tab-width` controls how wide a TAB
character (in the file) is displayed on screen.

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Pinsl · 2022-11-10 20:09

I have this in my config:

    (defvaralias 'c-basic-offset 'tab-width)
    (defvaralias 'cperl-indent-level 'tab-width)
    (defvaralias 'js-indent-level 'tab-width)

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YakumoYoukai · 2022-11-10 21:42

Uggh yeah, It took me too long to figure out this variable.  I hoped
it would just piggyback off of the C mode indentation logic,
particularly the ability to guess the indent size from the contents.

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TomSwirly · 2022-11-11 10:21

Dagnabbit!  Right, I even knew that about `tab-width` and forgot.

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TomSwirly · 2022-11-11 10:23

Just added this.

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TomSwirly · 2022-11-11 10:23

That seems to be right.  Upvotes all round!