index.js

// Cookie
// -------------
// Thanks to:
//  - http://www.nczonline.net/blog/2009/05/05/http-cookies-explained/
//  - http://developer.yahoo.com/yui/3/cookie/


var Cookie = exports;

var decode = decodeURIComponent;
var encode = encodeURIComponent;


/**
 * Returns the cookie value for the given name.
 *
 * @param {String} name The name of the cookie to retrieve.
 *
 * @param {Function|Object} options (Optional) An object containing one or
 *     more cookie options: raw (true/false) and converter (a function).
 *     The converter function is run on the value before returning it. The
 *     function is not used if the cookie doesn't exist. The function can be
 *     passed instead of the options object for conveniently. When raw is
 *     set to true, the cookie value is not URI decoded.
 *
 * @return {*} If no converter is specified, returns a string or undefined
 *     if the cookie doesn't exist. If the converter is specified, returns
 *     the value returned from the converter.
 */
Cookie.get = function(name, options) {
    validateCookieName(name);

    if (typeof options === 'function') {
        options = { converter: options };
    }
    else {
        options = options || {};
    }

    var cookies = parseCookieString(document.cookie, !options['raw']);
    return (options.converter || same)(cookies[name]);
};


/**
 * Sets a cookie with a given name and value.
 *
 * @param {string} name The name of the cookie to set.
 *
 * @param {*} value The value to set for the cookie.
 *
 * @param {Object} options (Optional) An object containing one or more
 *     cookie options: path (a string), domain (a string),
 *     expires (number or a Date object), secure (true/false),
 *     and raw (true/false). Setting raw to true indicates that the cookie
 *     should not be URI encoded before being set.
 *
 * @return {string} The created cookie string.
 */
Cookie.set = function(name, value, options) {
    validateCookieName(name);

    options = options || {};
    var expires = options['expires'];
    var domain = options['domain'];
    var path = options['path'];

    if (!options['raw']) {
        value = encode(String(value));
    }

    var text = name + '=' + value;

    // expires
    var date = expires;
    if (typeof date === 'number') {
        date = new Date();
        date.setDate(date.getDate() + expires);
    }
    if (date instanceof Date) {
        text += '; expires=' + date.toUTCString();
    }

    // domain
    if (isNonEmptyString(domain)) {
        text += '; domain=' + domain;
    }

    // path
    if (isNonEmptyString(path)) {
        text += '; path=' + path;
    }

    // secure
    if (options['secure']) {
        text += '; secure';
    }

    document.cookie = text;
    return text;
};


/**
 * Removes a cookie from the machine by setting its expiration date to
 * sometime in the past.
 *
 * @param {string} name The name of the cookie to remove.
 *
 * @param {Object} options (Optional) An object containing one or more
 *     cookie options: path (a string), domain (a string),
 *     and secure (true/false). The expires option will be overwritten
 *     by the method.
 *
 * @return {string} The created cookie string.
 */
Cookie.remove = function(name, options) {
    options = options || {};
    options['expires'] = new Date(0);
    return this.set(name, '', options);
};


function parseCookieString(text, shouldDecode) {
    var cookies = {};

    if (isString(text) && text.length > 0) {

        var decodeValue = shouldDecode ? decode : same;
        var cookieParts = text.split(/;\s/g);
        var cookieName;
        var cookieValue;
        var cookieNameValue;

        for (var i = 0, len = cookieParts.length; i < len; i++) {

            // Check for normally-formatted cookie (name-value)
            cookieNameValue = cookieParts[i].match(/([^=]+)=/i);
            if (cookieNameValue instanceof Array) {
                try {
                    cookieName = decode(cookieNameValue[1]);
                    cookieValue = decodeValue(cookieParts[i]
                            .substring(cookieNameValue[1].length + 1));
                } catch (ex) {
                    // Intentionally ignore the cookie -
                    // the encoding is wrong
                }
            } else {
                // Means the cookie does not have an "=", so treat it as
                // a boolean flag
                cookieName = decode(cookieParts[i]);
                cookieValue = '';
            }

            if (cookieName) {
                cookies[cookieName] = cookieValue;
            }
        }

    }

    return cookies;
}


// Helpers

function isString(o) {
    return typeof o === 'string';
}

function isNonEmptyString(s) {
    return isString(s) && s !== '';
}

function validateCookieName(name) {
    if (!isNonEmptyString(name)) {
        throw new TypeError('Cookie name must be a non-empty string');
    }
}

function same(s) {
    return s;
}