Caching function calculation results

cache.js

function cached(fn) {
  // Create an object to store the results returned after each function execution.
  const cache = Object.create(null);

  // Returns the wrapped function
  return function cachedFn(str) {

    // If the cache is not hit, the function will be executed
    if (!cache[str]) {
        let result = fn(str);

        // Store the result of the function execution in the cache
        cache[str] = result;
    }

    return cache[str];
  }
}

function computed(str) {    
    // Suppose the calculation in the funtion is very time consuming        
    console.log('bang');
    return 'a result';
}

const cachedComputed = cached(computed);
cachedComputed('first');
cachedComputed('first');