Very "Hello-world" for graphql server - Credit Udemy:GraphQL for Absolute Beginners: The Newbie Guide

server.graphql.ts

var {graphql, buildSchema} = require('graphql');
var schema = buildSchema (`
	type Query{
		hello : String
	}
`);

var root = {
	hello: () => {
		return 'Hello World.';
	}
};

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