# lastIndexOf

`import { lastIndexOf } from "destack:bytes";`

Return the last index of `needle`.

```ds title="lastIndexOf"
export function lastIndexOf(bytes: &'a readonly [uint8], needle: &'b readonly [uint8]): isize | undefined
```

[language/library/src/bytes/bytes.ds:198:203](https://github.com/destack-sh/destack/blob/main/language/library/src/bytes/bytes.ds#L198-L203)