prefixUrl

OpenAPI paths usually start with /, while raw ky rejects leading slash input when prefixUrl is set. Fetcher handles this mismatch for string URL calls.

const api = createFetcher<paths>({
  prefixUrl: 'https://example.com/api',
});

await api.get('/users/{id}', {
  params: { path: { id: '42' } },
});

The request is ultimately sent to https://example.com/api/users/42.

What is retried

If ky throws the known prefixUrl leading-slash error and the original input is a string that starts with /, fetcher retries the same call after stripping the leading slash.

It does not retry:

• absolute URL strings
• URL objects
• Request objects
• unrelated synchronous errors from a custom runner

Clearing prefixUrl

If you call extend({ prefixUrl: undefined }), the derived client no longer has a prefix URL. Leading slash string inputs then follow ky behavior and can throw invalid URL errors.