Variables in regexp with JavaScript client

I was able to get this resolved, but it looks like the / characters are required. If I remove them, I get an error from Dgraph:

Error: 2 UNKNOWN: Unexpected error while parsing regex arg: ife
  at Object.callErrorFromStatus (node_modules/@grpc/grpc-js/src/call.ts:81:24)
  at Object.onReceiveStatus (node_modules/@grpc/grpc-js/src/client.ts:334:36)
  at Object.onReceiveStatus (node_modules/@grpc/grpc-js/src/client-interceptors.ts:434:34)
  at Object.onReceiveStatus (node_modules/@grpc/grpc-js/src/client-interceptors.ts:397:48)