The de-facto GraphQL package in JavaScript, graphql.js, is a bit verbose. Use buildSchema() to make your life easier. You can use GraphQL’s schema definition language to write your schemas.

import { graphql, buildSchema } from 'graphql'

const schema = bulidSchema(`
  type Query {
    hello: String
  }
)`

const root = {
  hello () { return 'world' }
}

graphql(schema, '{ hello }', root)
  .then(res => { console.log(res) })
// => { data: { hello: 'world' } }

Without buildSchema(), you’ll have to write it using lower-level classes:

import {
  graphql,
  GraphQLSchema,
  GraphQLObjectType,
  GraphQLString
} from 'graphql'

var schema = new GraphQLSchema({
  query: new GraphQLObjectType({
    name: 'RootQueryType',
    fields: {
      hello: {
        type: GraphQLString,
        resolve() { return 'world' }
      }
    }
  })
})

graphql(schema, '{ hello }')
  .then(res => { console.log(res) })
// => { data: { hello: 'world' } }

You can see an example in the graphql.js documentation’s home page.