Project Euler Problem #20 : Factorial digit sum

My solution for Problem #20 on projecteuler.net

by Hilarius Doren

HTML

<div class="code">
    <a href="https://projecteuler.net/problem=20">Project Euler</a> Solution
    <br />Problem ID #20 : Factorial digit sum
    <br />
    <br />n! means n × (n − 1) × ... × 3 × 2 × 1
    <br />For example, 10! = 10 × 9 × ... × 3 × 2 × 1 = 3628800,
    <br />and the sum of the digits in the number 10! is 3 + 6 + 2 + 8 + 8 + 0 + 0 = 27.
    <br />
    <br />Find the sum of the digits in the number 100!
</div>
<div id="main"></div>

CSS

.code {
    font-family:'Courier';
    font-size: 12px;
    color: #000;
    background: #D0D0D0;
    padding: 10px 25px;
}

.red {
    color: red;
}

JavaScript

var strResult = '<br />The factorial of 100 is: ';
var result = 0;
function factorial(number) {
    if (number == 1) return 1;
    return number * factorial(number-1);
}
function sumOfDigits(number) {
    //takes the number and adds of the digits, as an example 321 would be 6 (3+2+1)
    var str = number.toString();
    var sum = 0;
    for (var x = -1; ++x < str.length;) sum += +str[x];
    return sum;
}
result = factorial(10);
strResult += result;
strResult += '<br/> And the sum of its digits is: ' + sumOfDigits(result);
    
$('#main').html(strResult);