Fibonacci Number Calculation Algorithm

This JavaScript code is written to demonstrate how to calculate the fibonacci numbers. For more information on fibonacci numbers, checkout this post

let data = {} 
function calculateFibonacci(num){   
    if(num <= 2){     
        return 1;   
    }   
    if(data[num]){
        return data[num];
    }
    fibNum = calculateFibonacci(num - 1) + calculateFibonacci(num - 2);   
    data[num] = fibNum;   
    return fibNum; 
}