Sharing typescript code between two projects in a monorepo with yarn 2 workspaces

Question

I want to set up a project with a client part (react-app), a server part (express) and a shared library (utils) in typescript. I use yarn 2 workspaces and wanted to avoid using larna (if possible). Unfortunately, I have not been able to make it work since few days (and a lot of googling...). When trying to run the client app I receive the error:

Cannot find module 'utils' or its corresponding type declarations. TS2307

Does anybody know what I am doing wrong?

This is my project structure:

• .yarn
• packages
  • client (created with create-react-app)
  • utils (created with yarn tsc --init)
  • server
• .pnp.js
• .yarnrc.yml
• package.json
• yarn.lock

package.json (root):

{
  "private": true,
  "name": "monorepo with shared library and yarn 2 workspaces",
  "workspaces": [
    "packages/*"
  ],
  "scripts": {
    "client": "yarn workspace client start",
    "server": "yarn workspace server start",
    "prepare": "yarn workspace utils build"
  }
}

utils/package.json:

{
    "name": "utils",
    "private": true,
    "version": "1.0.0",
    "main": "dist/index.js",
    "types": "dist/index.d.ts",
    "files": [
        "dist"
    ],
    "devDependencies": {
        "@types/node": "^14.14.22",
        "@typescript-eslint/eslint-plugin": "^4.14.0",
        "@typescript-eslint/parser": "^4.14.0",
        "eslint": "^7.18.0",
        "eslint-config-prettier": "^7.2.0",
        "eslint-plugin-prettier": "^3.3.1",
        "prettier": "^2.2.1",
        "typescript": "^4.1.3"
    },
    "scripts": {
        "build": "tsc -b --verbose"
    }
}

utils/src/index.ts:

function test() {
    console.log("this is a function from the shared library ");
}

export = {
    test
}

client/package.json

{
  "name": "client",
  "version": "0.1.0",
  "private": true,
  "dependencies": {
    "@testing-library/jest-dom": "^5.11.4",
    "@testing-library/react": "^11.1.0",
    "@testing-library/user-event": "^12.1.10",
    "@types/jest": "^26.0.15",
    "@types/node": "^12.0.0",
    "@types/react": "^16.9.53",
    "@types/react-dom": "^16.9.8",
    "react": "^17.0.1",
    "react-dom": "^17.0.1",
    "react-refresh": "^0.9.0",
    "react-scripts": "4.0.1",
    "typescript": "^4.0.3",
    "utils": "1.0.0",                 // also tried "utils": "workspace:packages/utils"
    "web-vitals": "^0.2.4"
  },
  "scripts": {
    "start": "react-scripts start --verbose",
    "build": "react-scripts build",
    "test": "react-scripts test",
    "eject": "react-scripts eject"
  },
  "eslintConfig": {
    "extends": [
      "react-app",
      "react-app/jest"
    ]
  },
  "browserslist": {
    "production": [
      ">0.2%",
      "not dead",
      "not op_mini all"
    ],
    "development": [
      "last 1 chrome version",
      "last 1 firefox version",
      "last 1 safari version"
    ]
  },
  "devDependencies": {
    "eslint-config-react-app": "^6.0.0"
  }
}

I added a simple import in the client/src/App.tsx for testing:

import React from "react";
import logo from "./logo.svg";
import "./App.css";
import shared from "utils";

...

Thank you!

Answer 1

I got it working. 'yarn workspace client add utils' made the trick.