javascript how to read and write data to cookies

function setCookie(name,value)
{
    var Days = 30;
    var exp = new Date(); 
    exp.setTime(exp.getTime() + Days*24*60*60*1000);
    document.cookie = name + "="+ escape (value) + ";expires=" + exp.toGMTString();
}

function getCookie(Name) {
    var search = "[" + Name + "]="
          if (document.cookie.length > 0) { // if there are any cookies
                    offset = document.cookie.indexOf(search) 
                    if (offset != -1) { // if cookie exists 
                              offset += search.length 
                              // set index of beginning of value
                              end = document.cookie.indexOf(";", offset) 
                              // set index of end of cookie value
                              if (end == -1) 
                                        end = document.cookie.length
                              return unescape(document.cookie.substring(offset, end))
                    } 
          }
}//:$