Neutrino Typescript

Transpiles TypeScript as part of the build process.

This follows the configuration suggested in the official TypeScript / Babel announcement.

Installation

1. Install dependencies:

   npm install --save-dev neutrinojs-typescript typescript

   (note that neutrino-typescript in NPM - without js - is an unrelated package which is unmaintained).

2. Include in .neutrinorc.js:

   const typescript = require('neutrinojs-typescript');
   // ...
   
   module.exports = {
    use: [
      typescript(), // must be first in use section
      // ...
      node(), // or whichever target you are using
    ],
   };

3. Include type checking in package.json scripts:

   {
    "scripts": {
      "prebuild": "rewrite-tsconfig",
      "prelint": "rewrite-tsconfig",
      "lint": "tsc"
    }
   },

   To combine this with other linting steps, you can join the commands like so:

   {
    "scripts": {
      "prebuild": "rewrite-tsconfig",
      "prelint": "rewrite-tsconfig",
      "lint": "existing lint command && tsc"
    }
   },

4. Run npm run lint to create the initial tsconfig.json file and test the integration.

tsconfig.json

A tsconfig.json file will be generated automatically by rewrite-tsconfig and should be included in your repository. It does not have to be included (the prelint script will generate it when needed), but including it is recommended because many IDEs will look for it to configure their own type checking.

If you prefer managing tsconfig.json yourself, simply remove rewrite-tsconfig from your NPM scripts. You will need to ensure it remains compatible with the webpack / babel configuration in .neutrinorc.js.

If you prefer using tsconfig.js (or a similar tsconfig-as-code tool), remove rewrite-tsconfig from your NPM scripts and set the content of tsconfig.js to:

const neutrino = require('neutrino');

module.exports = neutrino().tsconfig();

Customisation

Since rewrite-tsconfig replaces any tsconfig.json file in the project directory. You should specify customisations in .neutrinorc.js instead:

const typescript = require('neutrinojs-typescript');

module.exports = {
  use: [
    typescript({ tsconfig: {
      compilerOptions: {
        strict: true,
        allowJs: true,
        importsNotUsedAsValues: 'remove', // legacy behaviour
        typeRoots: [
          'src/types', // custom types directory
          'node_modules/@types',
        ],
      },
      include: ['some-other-dir'], // sources and tests are included by default
    } }),
  ],
};

Some settings cannot be customised due to babel compatibility requirements. If you attempt to change those settings, they will be ignored and a warning will be printed.

Generating declaration (.d.ts) files

If you are creating a library, you probably want to include a .d.ts file. This can be turned on by specifying declaration: true as normal in the tsconfig options:

const typescript = require('neutrinojs-typescript');

module.exports = {
  use: [
    typescript({ tsconfig: {
      compilerOptions: {
        declaration: true,
        declarationMap: true, // defaults to true
      },
    } }),
  ],
};

One declaration file will be generated for each entrypoint you have specified in mains. The file will be named to match the input file (for default neutrino configuration, this means you will get build/index.d.ts).

Linting with ESLint

If you want to use eslint with typescript, you can install the neutrinojs-typescript-eslint module.

Testing with Jest

This will work out-of-the-box with Jest, but you will need to install the Jest types:

npm install --save-dev @types/jest