Use Promises without unboxing them

PromisedValue.mjs

// Usage:
//    console.log(await new PromisedValue([1,2,3]).map(x => x * 2).filter(x => x % 2))
//
// instead of this:
//   console.log(await Promised.resolve([1,2,3])
//     .then(arr => arr.map(x => x * 2))
//     .then(arr => arr.filter(x => x % 2)))

export function PromisedValue(target) {
  target = Promise.resolve(target)

  const invoker = (...args) => PromisedValue(target.then((t) => t(...args)))

  return new Proxy(invoker, {
    get(_, name) {
      // passthrough to methods defined on Promise
      if (typeof target[name] === 'function') return target[name].bind(target)

      return PromisedValue(
        target.then((t) => {
          if (typeof t[name] === 'function') {
            return (...args) => {
              let result = t[name].apply(t, args)
              if (Array.isArray(result)) {
                result = Promise.all(result)
              }
              return PromisedValue(result)
            }
          }

          return t[name]
        })
      )
    }
  })
}