no-octal-escape

In a string, a backslash followed by digits from 0 to 7 is a character code in base 8. For example, "\251" is the copyright sign. Few readers know this form, and a digit typed right after it can change which character you get. Use \xA9 or \u{A9} instead.

\0 on its own (the null character) isn't reported.

Octal escapes are a syntax error in modules and in strict mode. .js files are linted as modules, so the rule only has something to report in .cjs files, or where your config sets sourceType to "commonjs" or "script".

Configure

Off by default. To turn it on:

[lint.rules]
"no-octal-escape" = "error" # or "warn"

Examples

Reported:

const notice = "Copyright \251 2026";

Not reported:

const notice = "Copyright \xA9 2026";
const long = "Copyright \u{A9} 2026";
const terminator = "\0";