Function parseProtocol

parseProtocol(url: string): string
Parse protocol from URL.

从 URL 中解析协议。
Parameters
- url: string
  The URL to parse the protocol from.
Returns string
The protocol extracted from the URL.
Throws
If the URL is not a valid URL.
Example
```
parseProtocol('http://example.com') // => http
parseProtocol('mailto:[email protected]') // => mailto
```
- Defined in src/url/parse-protocol.ts:20