Quick smaller version jq for JSON

json.sh

#!/usr/bin/env node

const { readFile } = require('fs/promises')
const { format, parse } = require('path')
const expected = { attending: v => /true|1|yes/i.exec(v) ? true : false }
const { interpreter, executable, args, flags } = processArgsForFlags(process.argv, expected)

console.log(interpreter)
console.log(executable)
console.log(args)
console.log(flags)

function processArgsForFlags(fromArgs, expected = {}) {
  let args = Array.from(fromArgs)
  let flags = {}
  let errors = []

  let interpreter = Object.assign(parse(args.shift()), { toString() { return format(this) }})
  let executable = Object.assign(parse(args.shift()), { toString() { return format(this) }})

  for (let i = 0; i < args.length; i++) {
    let search = /--(\w+)(?:=(.*))?/g.exec(args[i])
    if (search) {
      let param = search[1]
      let value = search[2]

      if (!value) {
        if (i + 1 < args.length) {
          value = args[i + 1]
          args.splice(i, 2)
        }
      }
      else {
        args.splice(i, 1)
        i-- // Decrement i to account for removed element
      }

      if (param in expected && typeof(expected[param]) == 'function') {
        value = expected[param](value)
      }
      else {
        if (typeof(expected[param]) !== 'function') {
          errors.push({message: 'Expected type parameter is not a function that converts string to value', param})
        }
      }

      flags[param] = value
    }
  }

  return {
    interpreter,
    executable,
    args,
    flags,
    errors,
  }
}