Javascript訪問Cookie的四個常用方法

Javascript訪問Cookie的四個基本方法無論是在建立頁面還是構建對象都會使用到，單獨拿出來備用：

// utility function called by getCookie()
function getCookieVal(offset) {
  var endstr = document.cookie.indexOf (";", offset);
  if (endstr == -1) {
    endstr = document.cookie.length;
  }
  return unescape(document.cookie.substring(offset, endstr));
}

// primary function to retrieve cookie by name
function getCookie(name) {
  var arg = name + "=";
  var alen = arg.length;
  var clen = document.cookie.length;
  var i = 0;
  while (i < clen) {
    var j = i + alen;
    if (document.cookie.substring(i, j) == arg) {
      return getCookieVal(j);
    }
    i = document.cookie.indexOf(" ", i) + 1;
    if (i == 0) break;
  }
  return null;
}

// store cookie value with optional details as needed
function setCookie(name, value, expires, path, domain, secure) {
  document.cookie = name + "=" + escape (value) +
    ((expires) ? "; expires=" + expires : "") +
    ((path) ? "; path=" + path : "") +
    ((domain) ? "; domain=" + domain : "") +
    ((secure) ? "; secure" : "");
}

// remove the cookie by setting ancient expiration date
function deleteCookie(name,path,domain) {
  if (getCookie(name)) {
    document.cookie = name + "=" +
      ((path) ? "; path=" + path : "") +
      ((domain) ? "; domain=" + domain : "") +
      "; expires=Thu, 01-Jan-70 00:00:01 GMT";
  }