How to fix Cannot use 'module' option with ts-node without 'esm' in TypeScript

TypeScriptINTERMEDIATEMEDIUM

This error occurs when ts-node detects ES module syntax (import/export) in your TypeScript code but ESM support is not enabled. ts-node requires explicit ESM configuration to work with ES modules, which is common in modern TypeScript projects using module: "ESNext" or similar settings.

What this error means

The error "Cannot use 'module' option with ts-node without 'esm'" happens when ts-node encounters ES module syntax (import/export statements) in your TypeScript code, but the runtime environment is not configured to support ES modules. ts-node needs to know whether to treat your code as CommonJS or ES modules. When your tsconfig.json specifies a module system like "ESNext", "ES2020", or "ES2015", but you're running ts-node without ESM flags, ts-node cannot properly execute the code. This is a configuration mismatch between your TypeScript compiler settings and your Node.js runtime configuration. TypeScript may be configured to output ES modules, but Node.js (and by extension ts-node) needs explicit instructions to load ES modules rather than the default CommonJS modules.

How to fix "Cannot use 'module' option with ts-node without 'esm'"

1Check your tsconfig.json module setting

First, verify what module system your TypeScript is configured to use:

json

// tsconfig.json
{
  "compilerOptions": {
    "module": "ESNext",  // or "ES2020", "ES2015"
    // ... other options
  }
}

If your module is set to an ES module value (ESNext, ES2020, ES2015, etc.), you need ESM support.

2Add --esm flag to ts-node command

When running ts-node with ES module configuration, add the --esm flag:

bash

# For direct execution
npx ts-node --esm your-file.ts

# For ts-node/register
node --loader ts-node/esm --experimental-specifier-resolution=node your-file.ts

This tells ts-node to enable ES module support.

3Set package.json type to "module"

If your project uses ES modules, add this to your package.json:

json

{
  "type": "module",
  "scripts": {
    "start": "ts-node --esm src/index.ts"
  }
}

This tells Node.js to treat .js files as ES modules by default.

4Update ts-node configuration

You can configure ts-node to always use ESM by creating a tsconfig.json for ts-node:

json

// tsconfig.json
{
  "ts-node": {
    "esm": true,
    "experimentalSpecifierResolution": "node"
  },
  "compilerOptions": {
    "module": "ESNext"
  }
}

Or use a ts-node configuration file:

json

// .ts-noderc.json
{
  "esm": true,
  "experimentalSpecifierResolution": "node"
}

5Use alternative execution methods

If you continue to have issues, try alternative approaches:

1. Use tsx instead of ts-node:

bash

npx tsx your-file.ts

2. Compile first, then run:

bash

npx tsc
node dist/index.js

3. Use Node.js with ts-node/esm loader:

bash

node --loader ts-node/esm --experimental-specifier-resolution=node your-file.ts

6Verify Node.js version compatibility

Ensure your Node.js version supports ES modules:

- Node.js 12.17.0+ for experimental ES modules
- Node.js 14.13.0+ for stable ES module support
- Node.js 16.0.0+ for improved ES module features

Check your version:

bash

node --version

Update if necessary:

bash

# Using nvm
nvm install --lts
nvm use --lts

How to fix Cannot use 'module' option with ts-node without 'esm' in TypeScript

What this error means

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How to fix "Cannot use 'module' option with ts-node without 'esm'"

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