bug#26750: 25.2; js-mode missing keywords

bug#26750: 25.2; js-mode missing keywords

[Yuen Ho Wong]

When in js-mode, some latest Javascript keywords are not
highlighted. After looking at js.el, js--keyword-re seems to be missing
the following:

"as", "await, "async", and "of".

"await" is treated as a "future reserved word" in ES6 and promoted to a
keyword in the latest ES8 spec draft.

"async" is treated as a keyword in the AsyncFunctionExpression rule in
ES8 draft.

"of" is treated as a keyword in the for-of iteration production rule in
ES6.

"as" is treated as a keyword in import * as statements in ES6.

References:
ES6: https://www.ecma-international.org/ecma-262/6.0/
ES8: https://tc39.github.io/ecma262/


In GNU Emacs 25.2.1 (x86_64-apple-darwin16.4.0)
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 'configure --prefix=/opt/local --without-ns --without-x --without-dbus
 --without-gconf --without-libotf --without-m17n-flt --without-gpm
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 /opt/local/share/info/emacs 'CFLAGS=-pipe -Os -arch x86_64'
 CPPFLAGS=-I/opt/local/include 'LDFLAGS=-L/opt/local/lib
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Configured features:
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  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8-unix

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bug#26750: [PATCH] add missing keywords to js-mode

[Ruslan Bekenev]

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Hi. It is my first contribution. 
I hope everything is correct with this PATCH and submission itself. 
In this patch added two missed keywords to `js--keyword-re` which are `as` and `of`. 
`async` and `await` are already there. 

---
 lisp/progmodes/js.el | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lisp/progmodes/js.el b/lisp/progmodes/js.el
index bae9e52bf0..02e63986d6 100644
--- a/lisp/progmodes/js.el
+++ b/lisp/progmodes/js.el
@@ -278,11 +278,11 @@ Match group 1 is the name of the macro.")

 (defconst js--keyword-re
   (js--regexp-opt-symbol
-   '("abstract" "async" "await" "break" "case" "catch" "class" "const"
+   '("abstract" "as" "async" "await" "break" "case" "catch" "class" "const"
      "continue" "debugger" "default" "delete" "do" "else"
      "enum" "export" "extends" "final" "finally" "for"
      "function" "goto" "if" "implements" "import" "in"
-     "instanceof" "interface" "native" "new" "package"
+     "instanceof" "interface" "native" "new" "package" "of"
      "private" "protected" "public" "return" "static"
      "super" "switch" "synchronized" "throw"
      "throws" "transient" "try" "typeof" "var" "void" "let"
--

-- 
Ruslan Bekenev


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bug#26750: [PATCH] add missing keywords to js-mode

[Noam Postavsky]

forcemerge 26750 31306
quit

Ruslan Bekenev <furyinbox@gmail.com> writes:

> Hi. It is my first contribution. 
> I hope everything is correct with this PATCH and submission itself. 
> In this patch added two missed keywords to `js--keyword-re` which are `as` and `of`. 
> `async` and `await` are already there. 

Hi, sorry your patch was overlooked for so long.  Unfortunately, I think
just adding keywords to js--keyword-re will not quite do the right
thing, based on https://debbugs.gnu.org/cgi/bugreport.cgi?bug=31306#5:

    Specially, "as" and "from" should only be highlighted in an import
    statement. "of" should only be highlighted in a for statement. Any other
    occurrances of "as", "from" and "of" should not be highlighted as they
    are legal identifiers outside of import and for statements respectively.

bug#26750: [PATCH] add missing keywords to js-mode

[Jimmy Yuen Ho Wong]

Technically, "async", "await" and "yield" can also be identifiers.
"async" should only be highlighted if it's followed by a function, arrow
function or a method. "await" should only be highlighted if it's inside
an async function, async arrow function or an async method. "yield"
should only be highlighted inside a generator function/arrow function
and method. But for all intends and purposes, you can put "await" and
"yield" into the list of keywords or you'll have to write a full blown
parser and AST in order to traverse back and forth. That's how Chrome
devtools does it anyway. Only "async", "as", "of" and "from" need
special handling.


On 28/04/2018 22:08, Noam Postavsky wrote:
> forcemerge 26750 31306
> quit
>
> Ruslan Bekenev <furyinbox@gmail.com> writes:
>
>> Hi. It is my first contribution. 
>> I hope everything is correct with this PATCH and submission itself. 
>> In this patch added two missed keywords to `js--keyword-re` which are `as` and `of`. 
>> `async` and `await` are already there. 
> Hi, sorry your patch was overlooked for so long.  Unfortunately, I think
> just adding keywords to js--keyword-re will not quite do the right
> thing, based on https://debbugs.gnu.org/cgi/bugreport.cgi?bug=31306#5:
>
>     Specially, "as" and "from" should only be highlighted in an import
>     statement. "of" should only be highlighted in a for statement. Any other
>     occurrances of "as", "from" and "of" should not be highlighted as they
>     are legal identifiers outside of import and for statements respectively.
>
>