How to pass additional flags to NPM scripts

FlagHelper.js

const DEFAULT_FLAG = '--options='

/**
 * Allow to pass additional flag in command line
 * @param {String} flag  - optionnal flag used in command line
 * 
 * Flags can be passed :
 * - either when defining the script in package.json : 
 *  "myscript": "somecommand param --options=opt1"
 * - when calling the script adding '--'
 *   > yarn run myscript -- --options=opt1,opt2
 */
function getOptions(flag = DEFAULT_FLAG) {
  return process.argv.slice(2)
    .filter(arg => arg.startsWith(flag))
    .map(arg => arg.replace(flag, '').split(','))
}

module.exports = {
  getOptions
}