feat: Implement client

[enisdenjo]

Complying with the GraphQL over HTTP Specification Working Draft (Jul 28, 2022).

Basic usage with authentication and request retries:

import { createClient, NetworkError } from 'graphql-http';
import { getSession } from './my-auth';

const client = createClient({
  url: 'http://unstable.service:4000/graphql',
  headers: async () => {
    const session = await getSession();
    if (session) {
      return {
        Authorization: `Bearer ${session.token}`,
      };
    }
  },
  shouldRetry: async (err: NetworkError, retries: number) => {
    if (retries > 3) {
      // max 3 retries and then report service down
      return false;
    }

    // try again when service unavailable, could be temporary
    if (err.response?.status === 503) {
      // wait one second (you can alternatively time the promise resolution to your preference)
      await new Promise((resolve) => setTimeout(resolve, 1000));
      return true;
    }

    // otherwise report error immediately
    return false;
  },
});

(async () => {
  let cancel = () => {
    /* abort the request if it is in-flight */
  };

  const result = await new Promise((resolve, reject) => {
    let result;
    cancel = client.subscribe(
      {
        query: '{ hello }',
      },
      {
        next: (data) => (result = data),
        error: reject,
        complete: () => resolve(result),
      },
    );
  });

  expect(result).toEqual({ hello: 'world' });
})();

[enisdenjo]

🎉 This PR is included in version 1.0.0 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot 📦🚀