Convert TypeScript tsconfig paths to webpack alias paths

resolve-tsconfig-path-to-webpack-alias.js

const { resolve } = require('path');

/**
 * Resolve tsconfig.json paths to Webpack aliases
 * @param  {string} tsconfigPath           - Path to tsconfig
 * @param  {string} webpackConfigBasePath  - Path from tsconfig to Webpack config to create absolute aliases
 * @return {object}                        - Webpack alias config
 */
function resolveTsconfigPathsToAlias({
    tsconfigPath = './tsconfig.json',
    webpackConfigBasePath = __dirname,
} = {}) {
    const { paths } = require(tsconfigPath).compilerOptions;

    const aliases = {};

    Object.keys(paths).forEach((item) => {
        const key = item.replace('/*', '');
        const value = resolve(webpackConfigBasePath, paths[item][0].replace('/*', '').replace('*', ''));

        aliases[key] = value;
    });

    return aliases;
}

module.exports = resolveTsconfigPathsToAlias;

tsconfig.json

{
    "compilerOptions": {
        "module": "commonjs",
        "moduleResolution": "node",
        "outDir": "./dist",
        "allowJs": true,
        "target": "es6",
        "jsx": "react",
        "sourceMap": true,
        "noImplicitAny": true,
        "strictNullChecks": true,
        "baseUrl": "./",
        "lib": [
            "DOM",
            "ES5",
            "ES6",
            "es2017.object"
        ],
        "paths": {
            "Root/*": ["src/*"],
            "Components/*": ["src/components/*"],
            "Data/*": ["src/data/*"],
        }
    },

usage.tsx

import Banner from 'Components/banner';

webpack.config.js

// add paths to webpack

const resolveTsconfigPathsToAlias = require('./resolve-tsconfig-path-to-webpack-alias');

module.exports = {
  // ...
  resolve: {
    // ...
    alias: resolveTsconfigPathsToAlias({
	    tsconfigPath: '../tsconfig.json', // Using custom path
	    webpackConfigBasePath: '../', // Using custom path
    }),
  }
}

It's probably not, just a quirk of how ours are setup (our path prefixes point directly to src/ in your example, not to the folder containing src).

Definitely useful, I used to maintain three mappings. One for tsconfig, one for jest and one for Webpack. I set this up yesterday and a Jest equivalent the other day so now I just need to maintain one set of mapping which is great.

Works great, many thx @nerdyman

Great idea! Thank you!

However, there're couple of things can be improved. I wrote my modification which helps improve:

• Handle and ignore cases in which paths.values is empty.
• Cleaner code as it's written in a more declarative manner.
• More performant as it doesn't alter the object, instead it returns a constant which can be cached by either Node.js or Webpack.

See https://gist.github.com/phuctm97/7470a3b981fd80a501b4047e1e99a9f4 for more details or appreciation. Thank you!

const path = require('path');

/**
 * Helper function infers Webpack aliases from tsconfig.json compilerOptions.baseUrl and
 * compilerOptions.paths.
 *
 * @param {string} tsconfigPath - Path to tsconfig.json (Can be either relative or absolute path).
 * @return {object} An object representing corresponding Webpack alias.
 */
module.exports = (tsconfigPath = './tsconfig.json') => {
  const tsconfig = require(tsconfigPath);
  const { paths, baseUrl } = tsconfig.compilerOptions;

  return Object.fromEntries(Object.entries(paths)
    .filter(([, pathValues]) => pathValues.length > 0)
    .map(([pathKey, pathValues]) => {
      const key = pathKey.replace('/*', '');
      const value = path.resolve(path.dirname(tsconfigPath),
        baseUrl, pathValues[0].replace('/*', ''));
      return [key, value];
    }));
};

Not sure you folks are aware of this https://www.npmjs.com/package/tsconfig-paths-webpack-plugin. May be it can help someone in the future.

At lease tsconfig-paths-webpack-plugin doesn't work with webpack:^5:11.1 as it seems now.
I really appreciate this @nerdyman

Not sure you folks are aware of this https://www.npmjs.com/package/tsconfig-paths-webpack-plugin. May be it can help someone in the future.

this plugins replaces the context of resolve.alias object so u will not be able to add any custom aliases to your webpack configuration, and will be left in hands with only the one mentioned in tsconfig - what is kinda .... complicated )

@MisaGu Have you heard of the spread operator?

// add paths to webpack

const resolveTsconfigPathsToAlias = require('./resolve-tsconfig-path-to-webpack-alias');

module.exports = {
  // ...
  resolve: {
    // ...
    alias: {
      ...resolveTsconfigPathsToAlias({
	    tsconfigPath: '../tsconfig.json', // Using custom path
	    webpackConfigBasePath: '../', // Using custom path
      }),
      Utilities: path.resolve(__dirname, 'src/utilities/'),
      Templates: path.resolve(__dirname, 'src/templates/'),
    }
  }
}

@nerdyman It seems to me that this gist is missing the baseUrl. I had to edit to this to get it working.

const { resolve } = require('path');

/**
 * Resolve tsconfig.json paths to Webpack aliases
 * @param  {string} tsconfigPath           - Path to tsconfig
 * @param  {string} webpackConfigBasePath  - Path from tsconfig to Webpack config to create absolute aliases
 * @return {object}                        - Webpack alias config
 */
function resolveTsconfigPathsToAlias({
  tsconfigPath = './tsconfig.json',
  webpackConfigBasePath = __dirname,
} = {}) {
  const { paths, baseUrl } = require(tsconfigPath).compilerOptions;

  const aliases = {};

  Object.keys(paths).forEach((item) => {
    const key = item.replace('/*', '');
    const value = resolve(webpackConfigBasePath, baseUrl, paths[item][0].replace('/*', '').replace('*', ''));

    aliases[key] = value;
  });

  return aliases;
}

module.exports = resolveTsconfigPathsToAlias;

there is an issue in this configuration, because the first matched alias is selected instead of the most specific one

@its-dibo moved more specific first in the tsconfig paths as a workaround...