02-Project-Euler-Solve-Javascript.js

/* 
Even Fibonacci numbers
Problem 2

Each new term in the Fibonacci sequence is generated by adding the previous two terms. By starting with 1 and 2, the first 10 terms will be:

1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...

By considering the terms in the Fibonacci sequence whose values do not exceed four million, find the sum of the even-valued terms.

https://projecteuler.net/problem=2

*/


let limit = 4000000
let fibonacci = 1
let fibonacci_prev = 1
let fibonacci_next = 1
let result = 0

while (fibonacci < limit) {
    fibonacci = fibonacci_prev + fibonacci_next
    fibonacci_prev = fibonacci_next
    fibonacci_next = fibonacci

    if (fibonacci % 2 == 0) {
        result += fibonacci
    }
}

console.log(result)