bug#20915: 25.0.50; [js-mode] electric annoyances

[Rasmus]

Hi,

Electric layout doesn't always quite work to my liking in js-mode.

Start with Emacs -q and try the following example.

      x.map(function(d) {return f(x);});

When electric layout mode is on this is typed as

     x.map(function(d){
         return f(d);
     };

Which IMO looks bad for an inline, anonymous function which should just be
inlined.

If electric indentation mode is on, the following characters are bound by
default.

(mapcar 'char-to-string electric-indent-chars)
   => ("{" "}" "(" ")" ":" ";" "," " ")

I think that might be a bit too many....  Consider if I'm using my own
indentation style (e.g. chain syntax as used with d3.js), my manual
indentation is is ruined when I type in basically any function. 

Consider:

var plot = {}; var plot.scale = {};
plot.scale.y = d3.scale.ordinal()
                       .domain(bar.ybins)
                       .rangeRoundBands([plot.height, 0], 0.1);

Typing the *third line*, I get something like (with electric indent and
electric layout):

plot.scale.y = d3.scale.ordinal()
                       .domain(bar.ybins)
    .rangeRoundBands([plot.height, 0
                     ], 0.1);
       

I don't know if it is even possible for electric indent mode to somehow
guess that things are indented to an unknown style....

Thanks,
Rasmus

In GNU Emacs 25.0.50.2 (x86_64-unknown-linux-gnu, GTK+ Version 3.16.4)
 of 2015-06-21 on x200s
Repository revision: 821a3633564f36857968c7fe2b8bb6681a895905
Windowing system distributor `The X.Org Foundation', version 11.0.11702000
Configured using:
 `configure --prefix=/usr --sysconfdir=/etc --libexecdir=/usr/lib
 --localstatedir=/var --mandir=/usr/share/man
 --pdfdir=/usr/share/doc/emacs/pdf --with-sound=alsa --with-x-toolkit=gtk3
 --with-xft 'CFLAGS=-march=x86-64 -mtune=generic -O2 -pipe
 -fstack-protector-strong --param=ssp-buffer-size=4'
 CPPFLAGS=-D_FORTIFY_SOURCE=2
 LDFLAGS=-Wl,-O1,--sort-common,--as-needed,-z,relro'

-- 
One thing that is clear: it's all down hill from here