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
    }),
  }
}

Hi!

There will be an error if the file does not have the 'paths' section

• [webpack-cli] TypeError: Cannot convert undefined or null to object

There will be an error if there is an extra comma or comment

• [webpack-cli] SyntaxError: tsconfig.json: Unexpected token ']', ..."*",},
  "... is not valid JSON

Here is the solution. I'll leave it here, maybe someone will find it useful.

// tsconfig.json
{
  "compilerOptions": {
    // comment
    "paths": {
      "Root/*": ["src/*",],
      "Components/*": ["src/components/*",],
      "Data/*": ["src/data/*",],
    }
  },
}

// tsconfig-paths.mjs
import { dirname, resolve } from 'node:path';
import ts from 'typescript';

/** @typedef {Record<"compilerOptions", ts.server.protocol.CompilerOptions>} CompilerOptions */

const tsParsedCmd =
  /** @type {Record<"raw", CompilerOptions>} */
  (
    ts.getParsedCommandLineOfConfigFile('tsconfig.json', undefined, {
      ...ts.sys,
      onUnRecoverableConfigFileDiagnostic(diagnostic) {
        throw new Error(`${diagnostic.messageText}`);
      },
    })
  );

export function tsconfigPaths() {
  const res = /** @type {ts.MapLike<string[]>} */ ({});
  const { paths } = tsParsedCmd.raw.compilerOptions;
  if (paths) {
    for (const k of Object.keys(paths)) {
      const val = paths[k];
      res[dirname(k)] = val.map((path) => {
        return resolve(process.cwd(), dirname(path));
      });
    }
  }
  return res;
}

// webpack.config.mjs
/** @type {import("webpack").Configuration} */
export default {
  resolve: {
    alias: tsconfigPaths(),
  },
}