# no-octal-escape

> Disallow octal escape sequences such as `\251` in strings

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"`.

{/* Generated by src/codegen/lint-rule-docs.ts. Do not edit this section. */}

## Configure

Off by default. To turn it on:

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

{/* End of the generated section. */}

## Examples

Reported:

{/* bad {"filename": "notice.cjs"} */}
```js notice.cjs
const notice = "Copyright \251 2026";
```

Not reported:

{/* good {"filename": "notice.cjs"} */}
```js notice.cjs
const notice = "Copyright \xA9 2026";
const long = "Copyright \u{A9} 2026";
const terminator = "\0";
```