Regular expressions aren't properly highlighted in certain scenarios

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
42/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Stale
Tech stack
javascript, typescript
Domain
tooling

Research direction

Start by reproducing the supplied JavaScript snippets in VS Code, then locate the TypeScript TextMate grammar rules responsible for regular-expression literals. Compare highlighting in each listed context and in the nested example; done means the regexes and surrounding code are highlighted correctly without breaking later constructs.

Written by the indexing model from the issue text.

Description

in vscode 1.53.1

/foo/;
return /foo/;
throw /foo/;

yield* /foo/;
yield /foo/;
await /foo/;

export default /foo/;


if(_) /foo/;
else /foo/;

while(_) /foo/;

for(;;) /foo/;
for(_ in /foo/) /foo/;

with(_) /foo/;

do /foo/;
while(_);


void /foo/;
typeof /foo/;
/foo/ in /foo/;
/foo/ instanceof /foo/;
new /foo/;
!class extends /foo/ {};

/foo/[/foo/];
!/foo/;
~/foo/;
+/foo/;
-/foo/;
++/foo/;
--/foo/;
/foo/++;
/foo/--;

looks like this:

as can be seen, regular expressions aren't properly highlighted:

  • after throw/export default
  • after await/yield (but not yield*)
  • after while(), for(), with(), do, else (but not if())
  • after in/of (in for..in/for..of)
  • after void/typeof/new
  • as either operand of in/instanceof
  • after extends (in class)
  • after unary ++/--

worse yet, this can break the highlighting of surrounding code:

yield /[[]/;
if(1) {
	foo["bar"]();
	a: { break a; }
} else return 123;

Dominant language
TypeScript
Stars
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Forks
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