Spurious TypeScript warnings in monorepo with JavaScript component testing project

[MikeMcC399]

Current behavior

Running Cypress component testing in a Vite v5 or v6 based JavaScript project in a monorepo, where TypeScript is a transient dependency only in the root of the monorepo, results in additional warnings if the dependencies in the repo root are also installed:

(node:5542) ExperimentalWarning: --experimental-loader may be removed in the future; instead use register():
--import 'data:text/javascript,import { register } from "node:module"; import { pathToFileURL } from "node:url"; register("file%3A///home/mike/.cache/Cypress/14.0.0/Cypress/resources/app/node_modules/ts-node/esm/transpile-only.mjs", pathToFileURL("./"));'
(Use node --trace-warnings ... to show where the warning was created)
(node:5542) [DEP0180] DeprecationWarning: fs.Stats constructor is deprecated.
(Use node --trace-deprecation ... to show where the warning was created)

Desired behavior

The results of running Cypress component testing in a monorepo JavaScript project should be independent of whether the TypeScript dependencies in the root of the repo have been installed or not.

Test code to reproduce

Execute first:

git clone https://github.com/cypress-io/github-action
cd github-action
git clean -xfd # if repeating tests
npm ci
cd examples/component-tests
npm ci
npm test

which shows multiple node warnings (see above, and Debug Logs below), then execute:

rm -rf ../../node_modules
npm test

and confirm there is no longer any error for Node.js v22.14.x only the CJS deprecation warning is output:

The CJS build of Vite's Node API is deprecated. See https://vitejs.dev/guide/troubleshooting.html#vite-cjs-node-api-deprecated for more details.

Cypress Version

First reported on Cypress version: 14.0.0
Continues to be reproducible on Cypress version: 14.2.1

Node version

v22.13.0 LTS v22.14.0 LTS

Operating System

Ubuntu 24.04.2 LTS

Debug Logs

$ npm test

> example-component-tests@2.0.0 test
> cypress run --component


DevTools listening on ws://127.0.0.1:40257/devtools/browser/ced1c3dd-9c2a-40a8-94b8-12afea482130
(node:5542) ExperimentalWarning: `--experimental-loader` may be removed in the future; instead use `register()`:
--import 'data:text/javascript,import { register } from "node:module"; import { pathToFileURL } from "node:url"; register("file%3A///home/mike/.cache/Cypress/14.0.0/Cypress/resources/app/node_modules/ts-node/esm/transpile-only.mjs", pathToFileURL("./"));'
(Use `node --trace-warnings ...` to show where the warning was created)
(node:5542) [DEP0180] DeprecationWarning: fs.Stats constructor is deprecated.
(Use `node --trace-deprecation ...` to show where the warning was created)
The CJS build of Vite's Node API is deprecated. See https://vitejs.dev/guide/troubleshooting.html#vite-cjs-node-api-deprecated for more details.

====================================================================================================

  (Run Starting)

  ┌────────────────────────────────────────────────────────────────────────────────────────────────┐
  │ Cypress:        14.0.0                                                                         │
  │ Browser:        Electron 130 (headless)                                                        │
  │ Node Version:   v22.13.0 (/home/mike/n/bin/node)                                               │
  │ Specs:          1 found (Stepper.cy.jsx)                                                       │
  │ Searched:       **/*.cy.{js,jsx,ts,tsx}                                                        │
  └────────────────────────────────────────────────────────────────────────────────────────────────┘

with root dependencies installed:

  cypress:lifecycle:ProjectConfigIpc fork child process { CHILD_PROCESS_FILE_PATH: '/home/mike/.cache/Cypress/14.0.0/Cypress/resources/app/node_modules/@packages/server/lib/plugins/child/require_async_child.js', configProcessArgs: [ '--projectRoot', '/home/mike/github/cypress-io/github-action/examples/component-tests', '--file', '/home/mike/github/cypress-io/github-action/examples/component-tests/cypress.config.js' ], childOptions: { stdio: 'pipe', cwd: '/home/mike/github/cypress-io/github-action/examples/component-tests', execPath: '/home/mike/n/bin/node' } } +0ms
  cypress:lifecycle:ProjectConfigIpc found typescript in /home/mike/github/cypress-io/github-action/examples/component-tests +3ms
  cypress:lifecycle:ProjectConfigIpc using --experimental-specifier-resolution=node with --loader file:///home/mike/.cache/Cypress/14.0.0/Cypress/resources/app/node_modules/ts-node/esm/transpile-only.mjs +3ms
  cypress:lifecycle:ProjectConfigIpc detected node version 22.13.0, adding --no-experimental-detect-module option to child_process NODE_OPTIONS. +1ms
  cypress:lifecycle:ProjectConfigIpc detected node version 22.13.0, adding --no-experimental-require-module option to child_process NODE_OPTIONS. +0ms
  cypress:lifecycle:ProjectConfigIpc trigger the load of the file +17ms
(node:6747) ExperimentalWarning: `--experimental-loader` may be removed in the future; instead use `register()`:
--import 'data:text/javascript,import { register } from "node:module"; import { pathToFileURL } from "node:url"; register("file%3A///home/mike/.cache/Cypress/14.0.0/Cypress/resources/app/node_modules/ts-node/esm/transpile-only.mjs", pathToFileURL("./"));'
(Use `node --trace-warnings ...` to show where the warning was created)
(node:6747) [DEP0180] DeprecationWarning: fs.Stats constructor is deprecated.
(Use `node --trace-deprecation ...` to show where the warning was created)
  cypress:lifecycle:ProjectConfigIpc loadConfig:reply +729ms
The CJS build of Vite's Node API is deprecated. See https://vitejs.dev/guide/troubleshooting.html#vite-cjs-node-api-deprecated for more details.

when root dependencies not installed:

  cypress:lifecycle:ProjectConfigIpc fork child process { CHILD_PROCESS_FILE_PATH: '/home/mike/.cache/Cypress/14.0.0/Cypress/resources/app/node_modules/@packages/server/lib/plugins/child/require_async_child.js', configProcessArgs: [ '--projectRoot', '/home/mike/github/cypress-io/github-action/examples/component-tests', '--file', '/home/mike/github/cypress-io/github-action/examples/component-tests/cypress.config.js' ], childOptions: { stdio: 'pipe', cwd: '/home/mike/github/cypress-io/github-action/examples/component-tests', execPath: '/home/mike/n/bin/node' } } +0ms
  cypress:lifecycle:ProjectConfigIpc no typescript found, just use regular Node.js +3ms
  cypress:lifecycle:ProjectConfigIpc trigger the load of the file +12ms
  cypress:lifecycle:ProjectConfigIpc loadConfig:reply +468ms
The CJS build of Vite's Node API is deprecated. See https://vitejs.dev/guide/troubleshooting.html#vite-cjs-node-api-deprecated for more details.

Other

Related

• "Couldn't find tsconfig.json" error in JavaScript monorepo #30907
• TypeScript and package.json type module (ESM) shows "ExperimentalWarning: --experimental-loader" #30318
• [Spike] Investigate migrating off of ts-node #30426
• Vite v5 / v6 gives CJS deprecation warning with Component testing #29557

[AtofStryker]

going to close this issue as it will be resolved with Cypress 15, which is targeted for early July 2025