Memo function

main.js

function memo(fn) {
  const dict = {}
  let id
  const perform = { calls: 0, memoHits: 0 }
  return (...args) => {
    perform.calls++
    clearTimeout(id)
    id = setTimeout(() => {
      console.log(`memo hit rate = ${perform.memoHits}/${perform.calls}`)
    }, 1000)

    const key = JSON.stringify(args)
    if (dict[key] !== undefined) {
      perform.memoHits++
      return dict[key]
    }

    const output = fn(...args)
    dict[key] = output
    return output
  }
}

Memo function and log performance info