# `resolve-alpn` [![Node CI](https://github.com/szmarczak/resolve-alpn/workflows/Node%20CI/badge.svg)](https://github.com/szmarczak/resolve-alpn/actions) [![codecov](https://codecov.io/gh/szmarczak/resolve-alpn/branch/master/graph/badge.svg)](https://codecov.io/gh/szmarczak/resolve-alpn) ## API ### resolveALPN(options, connect = tls.connect) Returns an object with an `alpnProtocol` property. The `socket` property may be also present. ```js const result = await resolveALPN({ host: 'nghttp2.org', port: 443, ALPNProtocols: ['h2', 'http/1.1'], servername: 'nghttp2.org' }); console.log(result); // {alpnProtocol: 'h2'} ``` **Note:** While the `servername` option is not required in this case, many other servers do. It's best practice to set it anyway. **Note:** If the socket times out, the promise will resolve and `result.timeout` will be set to `true`. #### options Same as [TLS options](https://nodejs.org/api/tls.html#tls_tls_connect_options_callback). ##### options.resolveSocket By default, the socket gets destroyed and the promise resolves.
If you set this to true, it will return the socket in a `socket` property. ```js const result = await resolveALPN({ host: 'nghttp2.org', port: 443, ALPNProtocols: ['h2', 'http/1.1'], servername: 'nghttp2.org', resolveSocket: true }); console.log(result); // {alpnProtocol: 'h2', socket: tls.TLSSocket} // Remember to destroy the socket if you don't use it! result.socket.destroy(); ``` #### connect Type: `Function | AsyncFunction`\ Default: [`tls.connect`](https://nodejs.org/dist/latest-v16.x/docs/api/tls.html#tls_tls_connect_options_callback) **Note:** No matter which function is used (synchronous or asynchronous), it **must** accept a `callback` function as a second argument. The `callback` function gets executed when the socket has successfully connected. ## License MIT