Gatsby Typescript Plugin

An alternative to the official typescript plugin, with ts-loader & automatic type generation for your graphql queries (using graphql-code-generator)

Installation

yarn add typescript gatsby-plugin-ts

Add this to your gatsby config like any other plugins:

// gatsby-config.js
module.exports = {
  plugins: [
    `gatsby-plugin-ts`,
  ]
}

Unlike the official plugin, you’d have to bring your own tsconfig.json.

# generate a tsconfig if you have none
tsc --init

In order for this plugin to work right, you’d need to set your compile options like the following:

  "compilerOptions": {
    "target": "ESNext",    /* or at least ES2015 */
    "module": "ESNext",    /* or at least ES2015 */
    "lib": ["dom"],             /* <-- required! */
    "jsx": "preserve",          /* <-- required! */
    "moduleResolution": "node", /* <-- required! */

    /* for mixed ts/js codebase */
    "allowJS": true,
    "outDir": "./build"    /* this won't be used by ts-loader */
    /* other options... */
  }

Options

An example setup:

// gatsby-config.js
{
  resolve: `gatsby-plugin-ts`,
  options: {
    tsLoader: {
      logLevel: 'warn',
    },
    forkTsCheckerPlugin: {
      eslint: true,
    },
    fileName: `types/graphql-types.ts`,
    codegen: true,
    codegenDelay: 250,
    alwaysCheck: false,
  }
},

Gatsby files

• gatsby-config has to be a .js file
• gatsby-node is run directly by node, so it has to be a .js file as well. It is a shame, because in a complicated Gatsby app it is where a lot of logic live & will benefit from ts. As a work around, it can be built with tsc independently, in a script in package.json or somehow in gatsby’s pre-init hook.
• Gatsby’s global variable like __PATH_PREFIX__ can be handled by declaring this code somewhere:

// src/global.d.ts
declare const __PATH_PREFIX__: string

Code generation

By default, this plugin will build typing for your queries automatically to graphql-types.d.ts on every edit. Please note that the definition file should not be placed inside src since this triggers a never ending loop during development.

In order to take advantage of the generated code, user needs to name their query:

// src/pages/index.tsx

  export const pageQuery = graphql`
-   query {
+   query BlogIndex {
      site {
        siteMetadata {
          title
        }
      }
  ...

…and import it from the generated type file:

// src/pages/index.tsx

import { BlogIndexQuery } from '../graphqlTypes'

interface IBlogIndexProps {
  data: BlogIndexQuery;
  location: Location;
}

const BlogIndex: React.FC<IBlogIndexProps> = ({ data, location }) => {
  ...
}

Disable type checking in production

Previously this plugin disable type checking in production by default, which can be changed by setting alwaysCheck to true. Since 2.0.0 it no longer does this. If you want to preseve the previous behavior, please set the typeCheck option like below:

{
  resolve: 'gatsby-plugin-ts',
  options: {
    // Disable type checking in production
    typeCheck: process.env.NODE_ENV !== 'production',
  }
}