InClass-14.html

<h1>Fibonacci Sequence - Sum of Even Numbers Under ????</h1>
First Number: <input type="number" id="FirstNumber" value="1"><br>
Second Number: <input type="number" id="SecondNumber" value="2"><br>
Threshold: <input type="number" id="Threshold" value="400000"><br><br>
<input type="button" value="Go" onclick="Go()">
<h2 id="Answer"></h2>

<script>
    var firstNumberBox = document.getElementById("FirstNumber");
    var secondNumberBox = document.getElementById("SecondNumber");
    var thresholdBox = document.getElementById("Threshold");
    var answerTag = document.getElementById("Answer");

    function Go() {
        var firstNumber = parseInt(firstNumberBox.value);
        var secondNumber = parseInt(secondNumberBox.value);
        var nextNumber = firstNumber + secondNumber;
        var threshold = parseInt(thresholdBox.value);
        var sum = 0;
        if (firstNumber % 2 === 0) {
            sum = sum + firstNumber;
        } 
        if (secondNumber % 2 === 0) {
            sum = sum + secondNumber;
        }

        while (nextNumber < threshold) {
            if (nextNumber % 2 === 0) {
                sum = sum + nextNumber;
            }

            firstNumber = secondNumber;
            secondNumber = nextNumber;
            nextNumber = firstNumber + secondNumber;
        }
        answerTag.innerHTML = "Sum of Even: " + sum.toLocaleString();
    }
</script>