js取得指定のクッキーの具体的な実現

 
var cookieName = "cookie  "; 
var cookieValue = null;//  cookie value  
if (document.cookie && document.cookie != '') { 
var cookies = document.cookie.split(';');//      cookie      
for (var i = 0; i < cookies.length; i++) { 
var cookie = cookies[i];//      cookies   
if (cookie.substring(0, cookieName.length + 2).trim() == cookieName.trim() + "=") {//     cookie    cookie      
cookieValue = cookie.substring(cookieName.length + 2, cookie.length); 
break 
} 
} 
} 
if (cookieValue != "" && cookieValue != null) {//       cookie  
alert(cookieValue); 
} else {<span style="font-family: Arial, Helvetica, sans-serif;">//  cookie    </span> 
alert("not cookie!!!"); 
}