bug#9183: js-mode highlights quotes inside regexp character sets as string

[Štěpán Němec]

reopen 9183
thanks

On Fri, 05 Aug 2011 18:54:45 +0200
Stefan Monnier wrote:

>> The following is valid JavaScript:
>> /[']/.test(str)
>
>> js-mode erroneously highlights everything following `'' as a string.
>> Same problem with `"'.
>
> I installed the patch below which should fix this case and a few
> others.

Thanks, but it doesn't seem to fix anything, just mess things up in a
somewhat different way.

E.g., with the following in a JS buffer:

    /[']/.test(str);
    /ahoj/.test(str);
    /[']/.test(str);
    /[']/.test(str);

All of the first /[']/ is highlighted as a string, and everything from
the second single quote up to the third single quote is highlighted as a
string.

(Just in case, I downloaded the fixed js.el and loaded that with my
oldish Emacs 24 (started as emacs -Q), but I don't think that should
matter, right?)

> But I don't know how to solve it completely because I don't know
> Javascript enough to be sure exactly how to distinguish a /-division
> from a /-regexp from a /-comment-starter in all cases:
> - is something like
>
>     x = 1 + /a/.test("foo");
>
>   valid?

Yes, it's valid, although I suspect it would be considered bad style.

(BTW, in Debian there is a spidermonkey-bin package, which has minimal
dependencies and provides a `js' command, giving you a REPL.)

> If so, is there a list of infix operators somewhere?

I'd have to search for it just as you might have... There's this, for
instance:
https://developer.mozilla.org/en/JavaScript/Reference/Operators

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