@shopify/react-graphql/build/esm/links.mjs

Tools for creating type-safe and asynchronous GraphQL components for React

import { ApolloLink, Observable } from 'apollo-link';

function createSsrExtractableLink() {
  return new SsrExtractableLink();
}
class SsrExtractableLink extends ApolloLink {
  constructor(...args) {
    super(...args);
    this.operations = new Set();
  }

  resolveAll(then) {
    if (this.operations.size > 0) {
      return Promise.all([...this.operations]).then(then);
    }

    return then();
  }

  request(operation, nextLink) {
    if (nextLink == null) {
      throw new Error('SsrExtractableLink must not be the last link in the chain.');
    }

    let operationDone;
    const promise = new Promise(resolve => {
      operationDone = () => {
        this.operations.delete(promise);
        resolve();
      };
    });
    this.operations.add(promise);
    return new Observable(observer => {
      return nextLink(operation).subscribe({
        complete() {
          observer.complete();
          operationDone();
        },

        next: observer.next.bind(observer),
        error: observer.next.bind(observer)
      });
    });
  }

}

export { SsrExtractableLink, createSsrExtractableLink };