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process.env

An object containing the user environment variables.

Since Node 0.x Spec ↗

Syntax

process.env

Returns

object<string, string> — Environment variable names mapped to string values.

Examples

const port = process.env.PORT ?? '3000';
console.log(`listening on ${port}`);
Output 
listening on 3000

if (process.env.NODE_ENV === 'production') {
  console.log('prod mode');
} else {
  console.log('dev mode');
}
Output 
dev mode

Notes

Every value is a string, so `process.env.DEBUG === 'true'` not a boolean. Assigning to `process.env` mutates the process environment. Never commit secrets; load them from a `.env` file (Node 20.6+ supports `--env-file`). Reading a missing var returns `undefined`.

See also