fibonacci.js

// ================================================
// Fibonacci Sequence
// ================================================

function fibonacciGenerator(n) {
  var output = [];
  if (n === 1) {
    output = [0];
  } else if (n === 2) {
    output = [0, 1];
  } else {
    output = [0, 1];

    for (var i = 2; i < n; i++) {
      output.push(output[output.length - 2] + output[output.length - 1]);
    }
  }

  return output;
}

function fibonacci(num) {
  var a = 1,
    b = 0,
    temp;

  while (num >= 0) {
    temp = a;
    a = a + b;
    b = temp;
    num--;
  }
  return b;
}

// Recursive Fibonacci

function fibonacci(num) {
  if (num <= 1) return 1;

  return fibonacci(num - 1) + fibonacci(num - 2);
}

// Memoization Fibonacci

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

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

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