warning of unnecessary / accidental escape character in string literal about jshint HOT 1 OPEN

I like this idea! We should probably apply it to template literals and regular expression literals, too (although the character sets are slightly different in each context).

When it comes to regular expression literals, folks in an ES6-enabled environment can opt-in to this restriction thanks to the u flag:

// ES6-compliant runtimes tolerate the following unnecessary escape:
/\j/;

// ES6-complaint runtimes reject the following unnecessary escape:
/\j/u;

That behavior's part of the language, so it'll cause a syntax error today, anywhere. It's worth noting that JSHint implements that behavior because it gives us a head start on this feature request.

$ echo '/* jshint esversion: 6 */ void /\j/u;' | ./bin/jshint --verbose -
stdin: line 1, col 32, Invalid regular expression. (E016)

1 error

There may even be an opportunity to re-use some of that code...

Anyway, to preserve backwards compatibility, we'll have to implement this as a so-called "enforcing option" (that is: the behavior will have to be opt-in via a new linting rule).

I'm happy to assist anyone who wanted to write a patch for this. @KnickdaKnife since you suggested it, you get first dibs :) Let me know if you're interested!

from jshint.