method Socket.prototype.addMembership
Usage in Deno
```typescript import { Socket } from "node:node__dgram.d.ts"; ```
Socket.prototype.addMembership(multicastAddress: string,multicastInterface?: string,): void
Tells the kernel to join a multicast group at the given `multicastAddress` and `multicastInterface` using the `IP_ADD_MEMBERSHIP` socket option. If the `multicastInterface` argument is not
specified, the operating system will choose
one interface and will add membership to it. To add membership to every
available interface, call `addMembership` multiple times, once per interface.
When called on an unbound socket, this method will implicitly bind to a random
port, listening on all interfaces.
When sharing a UDP socket across multiple `cluster` workers, the`socket.addMembership()` function must be called only once or an`EADDRINUSE` error will occur:
```js
import cluster from 'node:cluster';
import dgram from 'node:dgram';
if (cluster.isPrimary) {
cluster.fork(); // Works ok.
cluster.fork(); // Fails with EADDRINUSE.
} else {
const s = dgram.createSocket('udp4');
s.bind(1234, () => {
s.addMembership('224.0.0.114');
});
}
```
void