Taylor Beseda

Check If Node.js File is Imported or Run as CLI

How to check if a Node.js (ESM) program is being executed on the command line or when imported by a Node.js process.

Use argv to find Node's entry

and compare it to the current filename. If this is script.js:

import { argv } from 'node:process'
import { fileURLToPath } from 'node:url'

const FILE = fileURLToPath(import.meta.url)
const isCLI = FILE === argv[1]

And this is main.js:

import script from './script.js'

In my testing, the following is consistent:

node script.js # isCLI => true
node main.js   # isCLI => false

from DynamoDB (5.7ms) to HTML (0.36ms) in 6.1ms