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

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.

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.

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

I have this in my config: (defvaralias 'c-basic-offset 'tab-width) (defvaralias 'cperl-indent-level 'tab-width) (defvaralias 'js-indent-level 'tab-width)

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.

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

Just added this.

That seems to be right. Upvotes all round!