JavaScript, cookies, set read and erake cookies

cookies.js

/**
 * Simple module for making cookies
 */
'use strict';
define(function() {
    return {
        createCookie: function(name, value, days) {
            var expires;
            if (days) {
                var date = new Date();
                date.setTime(date.getTime() + (days * 24 * 60 * 60 * 1000));
                expires = '; expires=' + date.toGMTString();
            } else {
                expires = '';
            }
            document.cookie = name + ' = ' + value + expires + '; path=/';
        },
        readCookie: function(name) {
            var nameEQ = name + '=';
            var ca = document.cookie.split(';');
            for (var i = 0; i < ca.length; i++) {
                var c = ca[i];
                while (c.charAt(0) === ' ') {
                    c = c.substring(1, c.length);
                }
                if (c.indexOf(nameEQ) === 0) {
                    return c.substring(nameEQ.length, c.length);
                }
            }
            return null;
        },
        eraseCookie: function(name) {
            this.createCookie(name, '', -1);
        }
    };
});