I want to use broadcastchannel for the supported browsers for unsupported ones like safai, i use the else code

I want to check whether the BroadcastChannel is supported or not and accordingly ride the code to else part

The below code gives error

if(BroadcastChannel) {
  new BroadcastChannel('oauthComplete').postMessage({
      email: 'mail@gmail.com',
      serviceName: '4sdbhfg@mx.co.us.user'
  });
}
else
  alert("Please close this tab and reopen");

How do I check whether BroadcastChannel is supported or not?