# Fibonacci and Efficency

## In this example below you will see how to do a Fibonacci and Efficency with some HTML / CSS and Javascript

This awesome code was written by Ticolyle, you can see more from this user in the personal repository.
You can find the original code on Codepen.io
• HTML
• JavaScript
``````<!DOCTYPE html>
<html lang="en" >

<meta charset="UTF-8">
<title>Fibonacci and Efficency</title>

<body>

<h1>Fib.js</h1>

<script  src="js/index.js"></script>

</body>

</html>
``````
``````
function fibonacciRecursive(n) {
if(n === 0 || n === 1) {
return 1;
}
return fibonacciRecursive(n-1) + fibonacciRecursive(n-2);
}

document.write('<h2>Recursive</h2>');
document.write(fibonacciRecursive(5));

function fibIt(n) {
if(n === 0 || n === 1) {
return 1;
}

var first = 1,
second = 1,
acc = 0;

for(var i = 2; i <= n; i++) {
acc = first + second;
first = second;
second = acc;
}

return acc;
}

document.write('<h2>Iterative</h2>')
document.write(fibIt(5));

function memoFib(num, memo) {
memo = memo || {};

if (memo[num]) return memo[num];
if (num <= 1) return 1;

return memo[num] = memoFib(num - 1, memo) + memoFib(num - 2, memo);
}

document.write('<h2>Memoization</h2>')
document.write(memoFib(5));
``````