basic get/set cookie

cookie.js

const cookie = {
    /**
     * Get a cookie's value
     * @param {String} name - Name of cookie
     * @returns {String} Value of cookie
     */
    get: function(name) {
        // unpack pairs
        let pairs = document.cookie.split(/;\s*/);
        let header = `${name}=`;
        
        for (let i = 0; i < pairs.length; i++) {
            let pair = pairs[i];
            
            if (pair.indexOf(header) === 0) {
                return pair.substring(header.length, pair.length);
            }
        }
        
        return null;
    },
    /**
     * Set a cookie's value
     * @param {String} name - Name of cookie
     * @param {*} value - Value of cookie
     * @param {Object} [options={}] - Cookie optinos
     * @param {Number} [options.days] - Expiration from now in days
     * @param {String} [options.path] - Path of cookie
     * @param {String} [options.domain] - Domain of cookie
     * @returns {String} Value of cookie
     */
    set: function(name, value, options = {}) {
        let pairs = [
            `${name}=${(value || '')}`,
            `path=${options.path || '\\'}`
        ];
        
        if (options.days) {
            let oneDay = 24 * 60 * 60 * 1000;
            let date = new Date(new Date() + (options.days * oneDay));
            
            pairs.push(`expires=${date.toUTCString()}`);
        }
        
        if (options.domain) {
            pairs.push(`domain=${options.domain}`);
        }
        
        document.cookie = pairs.join(';');
    }
};