Generates schema of GraphQL for http://example.com/graphql

schema.js

import fetch from 'node-fetch';
import jsonfile from 'jsonfile';

const GQL = (query, variables) => ({query, variables})

const request = (...args) => {
    try {
        return fetch(...args)
    } catch (e) {
        return Promise.reject({errors:[e]});
    }
};

const {assign} = Object;
const API = (url, options) => body => request(url, assign({}, options, {body}));

const graphqlAPI = body => (new API('http://example.com/graphql', {
    method: 'POST',
    headers: {'Content-Type': 'application/json'},
}))(JSON.stringify(GQL(body))).then(res => res.json());

const getTypeInfo = type => graphqlAPI(`{
  __type(name: "${type.name}") {
    name
    description
    fields {
      name
      type {
        name
        kind
      }
    }
  }
}`);

const saveAs = (filename, obj) => jsonfile.writeFile(filename, obj, err => console.log(err));
const save = (obj) => saveAs(__dirname + '/schema.json', obj);

graphqlAPI(`{
    __schema {
        types {
            name
            kind
            ofType {
                name
                kind
            }
        }
        directives {
            name
            description
            locations
            args
        }
    }
}`).then(({data}) =>
    Promise.all(data.__schema.types.map(getTypeInfo))
        .then(types => types.map(({data:{__type}}) => __type))
        .then(types => ({data: {__schema: {types, directives: data.__schema.directives}}}))
        .then(save)
        //.then(data => {console.log(JSON.stringify(data))})
        .catch(e => console.error(e))
);