Editor: Syntax highlighting is erroneous when string contains `&`

[EmilyOng]

Note: There is no error in evaluation.

Reproduction

Not OK

1. When the string is xxxx&xxx
const foo = "a&b is parsed as variable.language and "; is parsed as string.

const foo = "a&b";

2. When the string is xxxx&

const foo = "a&";

This string matches the variable.language regex possibly.

OK

const foo = "ab";

[martin-henz]

This issue persists as of today.

[RichDom2185]

Should we just remove our custom js-slang syntax highlighting and use default JS one? I don't really see it as a "core" feature to maintain our own syntax highlighting rules (it's only going to get worse if we want to maintain highlighting rules for the other languages).

[martin-henz]

I think our syntax highlighting should reflect the focus on specific sublanguages, such as Source §1. Learners with prior knowledge are able to see quickly whether the feature they are using is included in the language.