// 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.

            function fibonacciEvenSum(number) {
                "use strict";
                var array = [1, 2], // initial values of fibonacci
                    nextFibonacci = 0, // container for next fibonacci value
                    result = 0; // container for sum of even fibonacci values

                while (true) {
                    nextFibonacci = array[array.length - 2] + array[array.length - 1]; // sums the last element and second to last element of array
                    if (nextFibonacci < number) { // to evaluate whether the next Fibonacci value is still less than number (or 4,000,000)
                        array.push(nextFibonacci); // pushes the next Fibonacci value onto the array
                    } else {
                        break; // if the next Fibonacci is greater than 'number' we exit the loop
                    }
                }

                array.forEach(function (value) { // loop through the array
                    if (value % 2 === 0) { // evaluate only if the value is an even number
                        result += value; // add the even fibonacci values to result variable
                    }
                });

                return result;
            }

            console.log(fibonacciEvenSum(4000000)); // Output: 4613732