Ciao,
a rule like this:
((node-is "statement_block") parent-bol 0)

works for function but brakes the indentation of expressione like this:
const Geek = (a, b) =>
  {
	return (a + " " + b);
  }


In the attached patch, I have added a new rule specifically for this case.

Vincenzo

In data sabato 22 marzo 2025 13:24:16 Ora standard dell’Europa centrale, Eli 
Zaretskii ha scritto:
> Ping!  Juri and Vincenzo, please chime in.
> 
> > Cc: 76704@debbugs.gnu.org
> > Date: Sun, 09 Mar 2025 12:00:16 +0200
> > From: Eli Zaretskii <eliz@gnu.org>
> > 
> > > Date: Sun, 02 Mar 2025 20:44:39 +0100
> > > From:  Fabian Brosda via "Bug reports for GNU Emacs,
> > > 
> > >  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> > > 
> > > Hi,
> > > 
> > > when using js-ts-mode instead of js-mode, braces, which are put on a
> > > separate line are indented one level too much.  Here is a simple example
> > > of how the indentation looks like, after using indent-region on the
> > > whole function:
> > > 
> > > ```
> > > function test(x)
> > > 
> > >     {
> > >     
> > > 	    if(x)
> > > 	    
> > > 	        {
> > > 	        
> > > 		        return a;
> > > 	        
> > > 	        }
> > > 	    
> > > 	    else
> > > 	    
> > > 	        {
> > > 	        
> > > 		        return b;
> > > 	        
> > > 	        }
> > >     
> > >     }
> > > 
> > > ```
> > > 
> > > The used tree-sitter grammar is downloaded from
> > > https://github.com/tree-sitter/tree-sitter-javascript.
> > > 
> > > Having braces on a separate line is probably not the most common for
> > > javascript, but using indent-region in the js-mode, does yield the
> > > expected result.  The js.el file does already contain a comment
> > > mentioning braces in js--treesit-indent-rules.  But even based on the
> > > git history it is not clear to me, what exactly is meant:
> > > 
> > > ```
> > > 
> > >        ;; "{" on the newline.
> > >        ((node-is "statement_block") parent-bol js-indent-level)
> > > 
> > > ```
> > > 
> > > Link:
> > > https://github.com/emacs-mirror/emacs/blob/master/lisp/progmodes/js.el#
> > > L3457
> > > 
> > > If I replace 'js-indent-level' with '0' in this line, the indentation
> > > would
> > > be correct, but this might have unwanted side-effects I overlooked.
> > > 
> > > My current emacs version:
> > > 
> > > GNU Emacs 30.1 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.24.48,
> > > cairo version 1.18.2)
> > > 
> > > Thanks for looking into this.
> > 
> > Juri and Vincenzo, any comments?