JavaScript を使用して Cookie を作成および読み取るにはどうすればよいですか?

function createCookie(name, value, days) {
    // Calculate expiration date if provided
    var expires = "";
    if (days) {
        var date = new Date();
        date.setTime(date.getTime() + (days * 24 * 60 * 60 * 1000));
        expires = "; expires=" + date.toGMTString();
    }
    
    // Create the cookie
    document.cookie = name + "=" + value + expires + "; path=/";
}

function getCookie(c_name) {
    var cookies = document.cookie.split(';');
    
    for (var i = 0; i < cookies.length; i++) {
        var cr = cookies[i].split('=');
        if (cr[0].trim() == c_name) {
            return unescape(cr[1]);
        }
    }
    
    return "";
}