A Comprehensive Guide to Using Apollo GraphQL with JavaScript

August 11, 2025

4 min read

A Comprehensive Guide to Using Apollo GraphQL with JavaScript

Apollo GraphQL is a powerful and flexible platform for building and managing GraphQL APIs. With Apollo Client and Apollo Server, developers can easily integrate GraphQL into both the frontend and backend of an application. Whether you’re building a new GraphQL API or integrating it into an existing app, Apollo provides a set of tools that make it easier to work with GraphQL.

In this blog, we’ll explore how to use Apollo GraphQL with JavaScript, providing examples for both the client-side and server-side. We’ll also address common issues that developers might encounter along the way.

Setting Up Apollo GraphQL on the Backend with Apollo Server

Apollo Server is a library that helps you set up a GraphQL server quickly. It works seamlessly with other GraphQL tools like Apollo Client, and it integrates well with frameworks like Express.

Installation

To get started, you’ll need to install the Apollo Server and GraphQL packages:

npm install apollo-server graphql

If you’re using Express, you can also install the apollo-server-express package:

npm install apollo-server-express express

Create a GraphQL Schema

In GraphQL, you define types that describe the shape of your data and operations like queries and mutations.

Let’s start by defining a simple schema with a Query type:

// schema.js
const { gql } = require("apollo-server");

const typeDefs = gql`
  type Query {
    hello: String
  }
`;

const resolvers = {
  Query: {
    hello: () => "Hello, world!",
  },
};

module.exports = { typeDefs, resolvers };

In this example, we define a Query type with a hello field, which returns a string.

Set Up the Apollo Server

Now, let’s create the Apollo Server instance and connect it to the schema you just defined.

// server.js
const { ApolloServer } = require("apollo-server");
const { typeDefs, resolvers } = require("./schema");

const server = new ApolloServer({
  typeDefs,
  resolvers,
});

server.listen({ port: 4000 }).then(({ url }) => {
  console.log(`Server ready at ${url}`);
});

In this code:

• We create an Apollo Server instance with the schema (typeDefs) and resolvers.
• The server listens on port 4000, and we log the server’s URL when it’s ready.

To run your server, execute:

node server.js

You can now query your GraphQL server by navigating to http://localhost:4000 and using the Apollo Server’s interactive playground.

Handling Mutations

Mutations are GraphQL’s way of modifying server-side data (similar to HTTP POST, PUT, DELETE). You can define mutations just like queries.

Here’s an example of adding a mutation to create a new item:

// schema.js
const { gql } = require("apollo-server");

const typeDefs = gql`
  type Query {
    hello: String
  }

  type Mutation {
    createItem(name: String!): String
  }
`;

const resolvers = {
  Query: {
    hello: () => "Hello, world!",
  },
  Mutation: {
    createItem: (_, { name }) => {
      return `Item ${name} created!`;
    },
  },
};

module.exports = { typeDefs, resolvers };

Now you can send a mutation query like:

mutation {
  createItem(name: "New Item") {
    item
  }
}

This will return a string confirming that the item has been created.

Setting Up Apollo Client on the Frontend

Once your backend is set up, you can query it using Apollo Client. This is an easy-to-use JavaScript client that can work with any GraphQL server.

Installation

Install Apollo Client and its dependencies:

npm install @apollo/client graphql

If you’re working with React, you can also install the React integration:

npm install @apollo/client react-apollo

Setting Up Apollo Client

First, set up Apollo Client by providing it with the URI of your GraphQL server (i.e., http://localhost:4000):

// client.js
import { ApolloClient, InMemoryCache, gql } from "@apollo/client";

const client = new ApolloClient({
  uri: "http://localhost:4000",
  cache: new InMemoryCache(),
});

client
  .query({
    query: gql`
      query {
        hello
      }
    `,
  })
  .then((result) => console.log(result.data));

In this example:

• The Apollo Client is set up to connect to the server at http://localhost:4000.
• We define a query that asks for the hello field, and the client sends the query to the server.

Using Apollo Client with React

If you’re using React, the Apollo Client can be integrated easily with the ApolloProvider component. Here’s how to set it up in a React application:

// App.js
import React from "react";
import { ApolloProvider, InMemoryCache, gql, useQuery } from "@apollo/client";

const client = new ApolloClient({
  uri: "http://localhost:4000",
  cache: new InMemoryCache(),
});

const GET_HELLO = gql`
  query {
    hello
  }
`;

const Hello = () => {
  const { data, loading, error } = useQuery(GET_HELLO);

  if (loading) return <p>Loading...</p>;
  if (error) return <p>Error: {error.message}</p>;

  return <p>{data.hello}</p>;
};

function App() {
  return (
    <ApolloProvider client={client}>
      <Hello />
    </ApolloProvider>
  );
}

export default App;

Sending a Mutation

To send a mutation, you can use the useMutation hook provided by Apollo Client:

// App.js
import React, { useState } from "react";
import { ApolloProvider, useMutation, gql } from "@apollo/client";

const CREATE_ITEM = gql`
  mutation CreateItem($name: String!) {
    createItem(name: $name)
  }
`;

const App = () => {
  const [itemName, setItemName] = useState("");
  const [createItem] = useMutation(CREATE_ITEM);

  const handleCreateItem = () => {
    createItem({ variables: { name: itemName } })
      .then((response) => alert(response.data.createItem))
      .catch((error) => console.error(error));
  };

  return (
    <div>
      <input
        type="text"
        value={itemName}
        onChange={(e) => setItemName(e.target.value)}
        placeholder="Item Name"
      />
      <button onClick={handleCreateItem}>Create Item</button>
    </div>
  );
};

export default App;

In this example:

• We define a mutation (CREATE_ITEM) to create an item.
• The useMutation hook is used to trigger the mutation, sending the name as a variable.

Troubleshooting Common Apollo GraphQL Issues

1. CORS Issues

If you’re running the frontend and backend on different ports, you might encounter CORS (Cross-Origin Resource Sharing) issues when trying to query the GraphQL server. You can fix this by enabling CORS on the Apollo Server:

// server.js
const { ApolloServer } = require("apollo-server");
const { typeDefs, resolvers } = require("./schema");

const server = new ApolloServer({
  typeDefs,
  resolvers,
  cors: {
    origin: "http://localhost:3000", // Allow requests from this domain
  },
});

server.listen({ port: 4000 }).then(({ url }) => {
  console.log(`Server ready at ${url}`);
});

Make sure to replace http://localhost:3000 with the actual frontend URL.

2. Missing Schema Fields or Incorrect Query Responses

If you receive an error like Cannot query field "X" on type "Query", ensure that:

• The field is defined in your schema.
• You are sending the correct query to the server (with correct field names).

Check the server logs for any errors in the resolver function.

3. Apollo Client Errors (e.g., network error)

If you’re getting network-related errors in the client-side application, check the following:

• Verify that the server is running and accessible.
• Double-check the Apollo Client uri configuration to make sure it’s pointing to the correct endpoint.
• Check if there’s any firewall, network issue, or CORS configuration blocking the requests.

4. Database Errors

If your Apollo Server is connected to a database and you’re encountering issues, check the following:

• Ensure that the database connection string is correct.
• Make sure the database server is running and accessible.
• Verify that you have set up the correct model schema if you’re using an ORM like TypeORM or Mongoose.

5. Query Complexity and Pagination

For large datasets, consider using pagination or query complexity limits to prevent excessive data fetching. Using @connection directives and pagination arguments (first, after, etc.) will improve performance and avoid performance bottlenecks.

query {
  users(first: 10, after: "cursor") {
    name
    age
  }
}

Conclusion

Apollo GraphQL provides a flexible and scalable way to build and query GraphQL APIs. It simplifies the process of setting up a GraphQL server and integrating it into a JavaScript application.

Whether you’re working with React on the frontend or building a server-side API with Apollo Server, the Apollo ecosystem makes it easy to handle GraphQL queries, mutations, and subscriptions.

By following the steps in this guide, you should have a basic understanding of how to set up Apollo Server and Apollo Client in a JavaScript environment. Additionally, we’ve covered common troubleshooting tips to help you resolve issues quickly when they arise.