how to let npm package bin run with experimental-modules option?

Question

Starting in Node v8.5.0, support for ES6 style modules

import x from 'x'

has been available by running node using the option --experimental-modules, as below:

node --experimental-modules test.mjs

Using the bin key in package.json you can easily create cli tools npm cli, by running npm link.

Unfortunately, when running in this manner, node is called without the optional --experimental-modules flag.

How can you use bin modules with --experimental-modules?

Here is an example

bin/healthcheck.mjs

import { connect } from 'amqplib'

let open = connect(process.env.RABBITMQ_URL);

const exit = ({healthy = true}) => {
  return healthy ? process.exit(0) : process.exit(1)
}

open.then(() => {
  exit({healthy: true})
}).catch((e) => {
  exit({healthy: false})
})

package.json

{
  "name": "my-cli",
  "bin": {
    "healthcheck": "./bin/healthcheck.mjs"
  }
}

running...

> npm link
> healthcheck
/usr/local/bin/healthcheck: line 1: import: command not found
/usr/local/bin/healthcheck: line 3: syntax error near unexpected token `('
/usr/local/bin/healthcheck: line 3: `let open = connect(process.env.RABBITMQ_URL);'

Answer 1

You can use a shebang at the top of the script

#!/bin/sh 
":" //# comment; exec /usr/bin/env node --experimental-modules "$0" "$@"

More details here: http://sambal.org/2014/02/passing-options-node-shebang-line/