Factorial example

factorial-cli.js

/*jslint node: true */
 
module.exports = function () {
    'use strict';
 
    var math = require('./math'),
        number;
 
    if (!process.argv[2]) {
        console.log('Use "node factorial-cli.js <number>" to get the factorial');
        process.exit(0);
    }
 
    number = process.argv[2];
 
    console.log(math.factorial(number));
};
 
module.exports();

math.js

/*jslint node: true */
 
module.exports = (function () {
    'use strict';
 
    exports.factorial = function (n) {
        var res = 1;
 
        while (n > 1) {
            res *= n;
            n -= 1;
        }
 
        return res;
    };
 
    return exports;
}());