I have to plete this exercise, and I am not getting the results I need.

The specifications are: Calculate the sum of all even numbers in a Fibonacci sequence for values under 10,000. The first few numbers summed would be: 2, 8, 34, 144, 610.

I have a fiddle that produces this output: 10, 44, 188, 798, 3382.

var x = 1;
var y = 2;
var sum = 0;
var limit = 10000;
var evensum = 2;

while ((x + y) < limit) {
    sum = x + y;
    x = y;
    y = sum;

    if (sum % 2 === 0) {
        evensum += sum;
    }
    console.log(evensum);
}

fiddle link

Could someone please help me figuring out the part I am missing to plete this exercise?

Thank you much.

UPDATE Thank you everyone who posted a solution. They all worked great.

I have to plete this exercise, and I am not getting the results I need.

The specifications are: Calculate the sum of all even numbers in a Fibonacci sequence for values under 10,000. The first few numbers summed would be: 2, 8, 34, 144, 610.

I have a fiddle that produces this output: 10, 44, 188, 798, 3382.

var x = 1;
var y = 2;
var sum = 0;
var limit = 10000;
var evensum = 2;

while ((x + y) < limit) {
    sum = x + y;
    x = y;
    y = sum;

    if (sum % 2 === 0) {
        evensum += sum;
    }
    console.log(evensum);
}

fiddle link

Could someone please help me figuring out the part I am missing to plete this exercise?

Thank you much.

UPDATE Thank you everyone who posted a solution. They all worked great.

• javascript
• fibonacci

• 3 You are printing cumulative sums. 10 = 2 + 8, 44 = 10 + 34, 188 = 44 + 144, etc. In other words you are getting equivalent results to the spec, only producing different output. – Jon Commented Mar 21, 2016 at 21:20
• Have you looked at all 288 results already on stack overflow? stackoverflow./search?q=Fibonacci+javascript – Charlie Commented Mar 21, 2016 at 21:25

4 Answers 4

You are printing out the summation of even numbers. If you want to log each even fib number you need to log sum variable:

if (sum % 2 === 0) {
    evensum += sum;
    console.log(sum); // <---- log here
}
// console.log(evensum);

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

fib[0] = 0;
fib[1] = 1;
for(i=2; i<=20; i++)
{
    // Next fibonacci number = previous + one before previous
    // Translated to JavaScript:
    fib[i] = fib[i-2] + fib[i-1];
    if(fib[i]%2==0){
      document.write(fib[i]+" ");
    }
}

Simply move your console.log line outside of your while loop.

while ((x + y) < limit) {
    sum = x + y;
    x = y;
    y = sum;

    if (sum % 2 === 0) {
        evensum += sum;
    }

    console.log('Sum: ' + sum);
}

console.log('Full Sum of even Fibonacci numbers: ' + evensum);

var x = 0
var y = 1
var sum = 0;
var limit = 10000;
var evensum = 0;

while ((x + y) < limit) {
  sum = x + y;
  x = y;
  y = sum;
  if (sum % 2 == 0) {
  console.log(sum);
 }
}

working fiddle - https://jsfiddle/dotnojq8/1/