npm install graphql

var { graphql, buildSchema } = require('graphql');

var schema = buildSchema(`
  type Query {
    hello: String
  }
`);

var root = { hello: () => 'Hello world!' };

graphql(schema, '{ hello }', root).then((response) => {
  console.log(response);
});

var express = require('express');
var graphqlHTTP = require('express-graphql');
var { buildSchema } = require('graphql');

var schema = buildSchema(`
  type Query {
    hello: String
  }
`);

var root = { hello: () => 'Hello world!' };

var app = express();
app.use('/graphql', graphqlHTTP({
  schema: schema,
  rootValue: root,
  graphiql: true,
}));
app.listen(4000, () => console.log('Now browse to localhost:4000/graphql'));

var express = require('express');
var graphqlHTTP = require('express-graphql');
var { buildSchema } = require('graphql');

var schema = buildSchema(`
  type User {
    id: String
    name: String
  }

  type Query {
    user(id: String): User
  }
`);

// Maps id to User object
var fakeDatabase = {
  'a': {
    id: 'a',
    name: 'alice',
  },
  'b': {
    id: 'b',
    name: 'bob',
  },
};

var root = {
  user: function ({id}) {
    return fakeDatabase[id];
  }
};

var app = express();
app.use('/graphql', graphqlHTTP({
  schema: schema,
  rootValue: root,
  graphiql: true,
}));
app.listen(4000);
console.log('Running a GraphQL API server at localhost:4000/graphql');