Sign Up for Free

RunKit +

Try any Node.js package right in your browser

This is a playground to test code. It runs a full Node.js environment and already has all of npm’s 1,000,000+ packages pre-installed, including apollo-link with all npm packages installed. Try it out:

require("graphql/package.json"); // graphql is a peer dependency. var apolloLink = require("apollo-link")

This service is provided by RunKit and is not affiliated with npm, Inc or the package authors.

apollo-link v1.2.14

Flexible, lightweight transport layer for GraphQL



apollo-link is a standard interface for modifying control flow of GraphQL requests and fetching GraphQL results, designed to provide a simple GraphQL client that is capable of extensions. The targeted use cases of apollo-link are highlighted below:

  • fetch queries directly without normalized cache
  • network interface for Apollo Client
  • network interface for Relay Modern
  • fetcher for

Apollo Link is the interface for creating new links in your application.

The client sends a request as a method call to a link and can recieve one or more (in the case of subscriptions) responses from the server. The responses are returned using the Observer pattern.

Apollo Link Chain

Results from the server can be provided by calling next(result) on the observer. In the case of a network/transport error (not a GraphQL Error) the error(err) method can be used to indicate a response will not be recieved. If multiple responses are not supported by the link, complete() should be called to inform the client no further data will be provided.

In the case of an intermediate link, a second argument to request(operation, forward) is the link to forward(operation) to. forward returns an observable and it can be returned directly or subscribed to.

  next: result => {
  error: error => {

Implementing a basic custom transport

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

export class CustomApolloLink extends ApolloLink {
  request(operation /*, forward*/) {
    //Whether no one is listening anymore
    let unsubscribed = false;

    return new Observable(observer => {
      somehowGetOperationToServer(operation, (error, result) => {
        if (unsubscribed) return;
        if (error) {
          //Network error
        } else {
          observer.complete(); //If subscriptions not supported

      function unsubscribe() {
        unsubscribed = true;

      return unsubscribe;


npm install apollo-link --save

RunKit is a free, in-browser JavaScript dev environment for prototyping Node.js code, with every npm package installed. Sign up to share your code.
Sign Up for Free