gatsby-plugin-typescript

Allows Gatsby to build TypeScript and TSX files. Does NOT run type checking during build (see Caveats).

This plugin is automatically included in Gatsby. The only reason you would need to explicitly use this plugin is if you need to configure its options.

How to customize usage

1. Include the plugin in your gatsby-config.js file with the specific options
1. Write your components in TSX or TypeScript.
1. Run TypeScript directly or with a build tool.
1. You're good to go.

> When creating pages programmatically, you can pass the .tsx filename directly as the component for createPage.

_Please note: If packages don't ship with TypeScript definitions you'll need to manually install those type definitions, e.g. for React. A typical Gatsby project would need: npm install --save-dev @types/react @types/react-dom @types/node_

Options

When adding this plugin to your gatsby-config.js, you can pass in options to override the default @babel/preset-typescript config.

``javascript
// gatsby-config.js
module.exports = {
plugins: [
{
resolve: gatsby-plugin-typescript,
options: {
isTSX: true, // defaults to false
jsxPragma: jsx, // defaults to "React"
allExtensions: true, // defaults to false
},
},
],
}
`

For more detailed documentation on the available options, visit https://babeljs.io/docs/en/babel-preset-typescript#options.
To add TypeScript Babel plugins (e.g. @babel/plugin-proposal-decorators), you can try using a custom .babelrc file.

Caveats

This plugin uses babel-plugin-transform-typescript
to transpile TypeScript. It does _not do type checking_. Also since the TypeScript
compiler is not involved, the following applies:

> Does not support namespaces.
> Workaround: Move to using file exports, or
> migrate to using the module { } syntax instead.
>
> Does not support const enums because those require
> type information to compile. Workaround: Remove the
> const, which makes it available at runtime.
>
> Does not support export = and import =, because those
> cannot be compiled to ES.next. Workaround: Convert
> to using export default and export const,
> and import x, {y} from "z".
>
> Does not support baseUrl.
> Workaround: use gatsby-plugin-root-import
> and configure it to point the baseUrl value (also set baseUrl option in tsconfig.json file).

https://babeljs.io/docs/en/babel-plugin-transform-typescript.html

Type checking

First of all you should set up your IDE so that type errors are surfaced.
Visual Studio Code is very good in this regard.

In addition, you can see the instructions in TypeScript-Babel-Starter
for setting up a type-check` task.