memoization.js

function memoization(func) {
  let cache = new Map();
  const getData = () => {
    if (cache[func]) {
      console.log("cache");
      return cache[func];
    } else {
      cache[func] = func();
      console.log("not cache");
      return cache[func];
    }
  };
  return getData;
}
const heavy = memoization(() => {
  const arr = [];
  for (let i = 0; i < 100000000; i++) {
    arr.push(i);
  }
  return arr;
});
const start = Date.now();
console.log(heavy());
const end = Date.now();
console.log(end - start);
console.log(heavy());
const end2 = Date.now();
console.log(end2 - end);