2) Even Fibonacci numbers

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.

by fosco

JavaScript

var sum = (function (a, b) {
    var sum = 0;
    while (b <= 4000000) {
        a = [b, b = a + b][0];

        if ((b % 2) === 0) {
            sum += b;
        }
    }
    return sum;
})(1, 1);

console.log(sum); //4613732