how to memoize javascript code

1// a simple pure function to get a value adding 10
2const add = (n) => (n + 10);
3console.log('Simple call', add(3));
4// a simple memoize function that takes in a function
5// and returns a memoized function
6const memoize = (fn) => {
7  let cache = {};
8  return (...args) => {
9    let n = args[0];  // just taking one argument here
10    if (n in cache) {
11      console.log('Fetching from cache');
12      return cache[n];
13    }
14    else {
15      console.log('Calculating result');
16      let result = fn(n);
17      cache[n] = result;
18      return result;
19    }
20  }
21}
22// creating a memoized function for the 'add' pure function
23const memoizedAdd = memoize(add);
24console.log(memoizedAdd(3));  // calculated
25console.log(memoizedAdd(3));  // cached
26console.log(memoizedAdd(4));  // calculated
27console.log(memoizedAdd(4));  // cached

1const memoizedValue = [];
2const clumsysquare = (num) => {
3  if ((memoizedValue[num] == !undefined)) {
4    return memoizedValue[num];
5  }
6
7  let result = 0;
8  for (let i = 1; i <= num; i++) {
9    for (let j = 1; j <= num; j++) {
10      result++;
11    }
12  }
13
14  memoizedValue[num] = result;
15  return result;
16};
17
18console.log(clumsysquare(190));
19console.log(clumsysquare(799));
20console.log(clumsysquare(4000));
21console.log(clumsysquare(7467));
22console.log(clumsysquare(9666));
23