I. Basic server

run webserver,
open altair (https://altair-gql.firebaseapp.com/) and set url to http://localhost:3000/graphql in Safari or in altair desktop (in Chrome problem with mixed content http vs https)

run query:

query{
  books {
    title
    author
  }
}

II. Query samples

add more queryes: sum and time.
Example of params, descriptions
Multiple results in one query

query{
  books {
    author
  }
  sum(n1:1, n2:2)
  time
}

another options to use multiple query in one request:

query queryName{
  sum1: sum(n1:1, n2:10)
  sum2: sum(n1:2, n2:20)
}

query with params: set variable: {"ten":10}

query sumWithParams($ten:Int!) {
  sum1: sum(n1:$ten, n2:1)
  sum2: sum(n1:$ten, n2:10)
}

III. Sample mutation

add subscription

run mutation

mutation{
  sayHi(name: "Mutation Sample")
}

watch server console

IV. Add subscriptions

add packages npm i graphql-subscriptions subscriptions-transport-ws
update index.js to register websocker subscriptions
update schema - add subscription and update mutation

set subscription url to ws://localhost:3000/subscriptions
add subscription to second tab

subscription {
  greeting
}

and run mutation in first tab

V. Add onConnect and onDisconnect

add onConnect and onDisconnect start and stop subscriptions
see console