fibonacci iterative javascript code example

Example 1: fibonacci javascript

function Fibonacci(num){
	var before = 0;
	var actual = 1;
	var next = 1;

	for(let i = 0; i < num; i++){
		console.log(next)
		before = actual + next;
		actual = next
		next = before
	}
}

Fibonacci(100);

Example 2: javascript fibonacci

function fibonacci(n) {
   return n < 1 ? 0
        : n <= 2 ? 1
        : fibonacci(n - 1) + fibonacci(n - 2);
}

console.log(fibonacci(4));

Example 3: js fibonacci sequence

var i;
    var fib = []; // Initialize array!

    fib[0] = 0;
    fib[1] = 1;
    for (i = 2; i <= 10; i++) {
      // Next fibonacci number = previous + one before previous
      // Translated to JavaScript:
      fib[i] = fib[i - 2] + fib[i - 1];
      console.log(fib[i]);
    }

Example 4: js to confirm fibonnaci

function isFibonacci(n) {
  var fib,
    a = (5 * Math.pow(n, 2) + 4),
    b = (5 * Math.pow(n, 2) - 4)

  var result = Math.sqrt(a) % 1 == 0,
    res = Math.sqrt(b) % 1 == 0;

  //fixed this line
  if (result || res == true) // checks the given input is fibonacci series
  {
    fib = Math.round(n * 1.618); // finds the next fibonacci series of given input
    console.log("The next Fibonacci number is " + fib);

  } else {
    console.log(`The given number ${n} is not a fibonacci number`);
  }
}

$('#fib').on("keyup change", function() {
  isFibonacci(+this.value)
})