export interface Options {
	/**
	Allow [protocol-relative URLs](https://en.wikipedia.org/wiki/URL#Protocol-relative_URLs) (e.g., `//example.com`) to be considered relative.

	Setting this to `false` treats URLs starting with two slash or backslash separators (`//`, `\\`, `/\`, `\/`) as absolute.

	This does not prevent open redirects. For redirect validation, parse against a fixed trusted HTTP(S) base, reject parse failures or mismatched origins/protocols, and use the parsed URL without further changes.

	__Note:__ Protocol-relative URLs are [technically relative](https://datatracker.ietf.org/doc/html/rfc3986#section-4.2) according to [RFC 3986](https://datatracker.ietf.org/doc/html/rfc3986), as they require the current page's protocol to resolve into absolute URLs. However, they can still navigate to external domains, which may be a security concern in certain contexts (e.g., preventing open redirects).

	@default true

	@example
	```
	import isRelativeUrl from 'is-relative-url';

	// Default behavior (allowProtocolRelative: true)
	isRelativeUrl('//example.com');
	//=> true

	// Strict mode (allowProtocolRelative: false)
	isRelativeUrl('//example.com', {allowProtocolRelative: false});
	//=> false
	```
	*/
	readonly allowProtocolRelative?: boolean;
}

/**
Check if a URL is relative.

@param url - The URL to check.

@example
```
import isRelativeUrl from 'is-relative-url';

isRelativeUrl('foo/bar');
//=> true

isRelativeUrl('https://sindresorhus.com/foo/bar');
//=> false

isRelativeUrl('//sindresorhus.com');
//=> true
```
*/
export default function isRelativeUrl(url: string, options?: Options): boolean;