Memo Lesson

cli.txt

node ./none-memo && node ./memo

none_memo: 10.005s
memo: 989.782ms

node ./none-memo && node ./memo
none_memo: 9.897s
memo: 974.547ms
node ./none-memo && node ./memo
none_memo: 9.953s
memo: 978.818ms

memo.js

const TIME_FLAG_MEMO = 'memo'

const toUpper = (str = '') => {
  return String(str).toUpperCase()
}

const complexCalc = (str = '') => {
  let result = ''
  for (let i = 0; i < 10e5; i++) {
    result = String(str).toUpperCase() + i
  }

  return result
}

const memoize = (fn) => {
  const cacheMap = {}

  return function (arg) {
    const cacheKey = String(arg)
    if (cacheMap[cacheKey]) {
      // console.log("hit cache", cacheKey);
      return cacheMap[cacheKey]
    }

    cacheMap[cacheKey] = fn(arg)
    return cacheMap[cacheKey]
  }
}

// This is our array of cases.
// it is need only for make a sequence to measure performance
const stringSize = 10
const strings = Array.from(
  'abbcdeeefhhjjkkkabbcdeeefhhjjkkkabbcdeeefhhjjkkkabbcdeeefhhjjkkkabbcdeeefhhjjkkkabbcdeeefhhjjkkk'
).map((c) => c.repeat(stringSize))

// Experiment #2

console.time(TIME_FLAG_MEMO)
const memoized = memoize(toUpper)
const memoizedCalc = memoize(complexCalc)

for (const str in strings) {
  memoized(strings[str])
  memoizedCalc(strings[str])
}

console.timeEnd(TIME_FLAG_MEMO)

none-memo.js

const TIME_FLAG_NONE_MEMO = 'none_memo'

const toUpper = (str = '') => {
  return String(str).toUpperCase()
}

const complexCalc = (str = '') => {
  let result = ''
  for (let i = 0; i < 10e5; i++) {
    result = String(str).toUpperCase() + i
  }

  return result
}

// This is our array of cases.
// it is need only for make a sequence to measure performance
const stringSize = 10
const strings = Array.from(
  'abbcdeeefhhjjkkkabbcdeeefhhjjkkkabbcdeeefhhjjkkkabbcdeeefhhjjkkkabbcdeeefhhjjkkkabbcdeeefhhjjkkk'
).map((c) => c.repeat(stringSize))
// Experiment #1
console.time(TIME_FLAG_NONE_MEMO)

for (const str in strings) {
  toUpper(strings[str])
  complexCalc(strings[str])
}

console.timeEnd(TIME_FLAG_NONE_MEMO)