TypeScript Setup and Apollo Client Integration

TypeScript

TypeScript is a statically-typed programming language developed and maintained by Microsoft. It is a superset of JavaScript, meaning that every valid JavaScript code is valid TypeScript code. TypeScript provides developers with additional features like type checking, autocomplete, and other tools to improve productivity and code quality.

Setting up TypeScript

To use TypeScript in your project, you first need to install the necessary packages. Run the following command to install TypeScript and its dependencies:

yarn add -D typescript @graphql-codegen/cli @graphql-codegen/client-preset @graphql-typed-document-node/core

Next, create a configuration file for GraphQL Code Generator called codegen.ts:

import { CodegenConfig } from '@graphql-codegen/cli';

const config: CodegenConfig = {
  schema: '<URL_OF_YOUR_GRAPHQL_API>',
  documents: ['src/**/*.{ts,tsx}'],
  generates: {
    './src/__generated__/': {
      preset: 'client',
      plugins: [],
      presetConfig: {
        gqlTagName: 'gql',
      },
    },
  },
  ignoreNoDocuments: true,
};

export default config;

Finally, add the following scripts to your package.json file:

"scripts": {
  "compile": "graphql-codegen",
  "watch": "graphql-codegen -w"
}

By running yarn run compile or yarn run watch, you will generate types based on the schema file or GraphQL API you provided in codegen.ts.

Using TypeScript with Apollo Client

TypeScript is often used in conjunction with frameworks like Apollo Client, which provides a GraphQL client for TypeScript-based applications. Using TypeScript with Apollo Client allows you to ensure type safety for the inputs and results of your GraphQL operations.

For example, you can use the following code snippet to define a type for a GraphQL query with parameters:

const GET_ROCKET_INVENTORY: TypedDocumentNode<RocketInventoryData, RocketInventoryVars> = gql`query GetRocketInventory($year: Int!) {rocketInventory(year: $year) {id model year stock}}`;

Here, RocketInventoryData and RocketInventoryVars are the types of the data and variables respectively, which are inferred by TypeScript.

Conclusion

TypeScript provides a rich set of features for static type checking and code generation, which can help catch bugs and improve the overall developer experience. By using TypeScript with frameworks like Apollo Client, you can ensure type safety for the inputs and results of your GraphQL operations.