用JavaScript操作cookie

寫入和讀取Cookie是一種常見的功能，可惜JavaScript對此的直接支援並不算完善，下面是幾個操作Cookie的函數，用起來還是蠻方便的。

// utility function to retrieve an expiration date in proper

// format; pass three integer parameters for the number of days, hours,

// and minutes from now you want the cookie to expire (or negative

// values for a past date); all three parameters are required,

// so use zeros where appropriate

function getExpDate(days, hours, minutes) {

    var expDate = new Date( );

    if (typeof days == "number" && typeof hours == "number" &&

        typeof hours == "number") {

        expDate.setDate(expDate.getDate( ) + parseInt(days));

        expDate.setHours(expDate.getHours( ) + parseInt(hours));

        expDate.setMinutes(expDate.getMinutes( ) + parseInt(minutes));

        return expDate.toGMTString( );

    }

}

  

// 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 "";

}

  

// 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";

    }

}

將上面的幾個js命名為cookie.js，下面示範其基本用法

<script type="text/javascript" src="cookie.js"></script>

<script type="text/javascript">

   function foo()

   {

         var name = document.getElementById("name").value;

         if(name)

         {

              setCookie("name",name);

         }

         document.getElementById("show").innerHTML+=("NEWEST NAME :"+ getCookie("name") + "<br>");

   }

</script>

Chapter 1.9 example

<br>

<input type="text" id="name" size="20" />

<input type="button" value="setCookie" onclick="foo()" />

<div id="show"></div>

可以同時開兩個視窗看看，輸入框不輸入值，按按鈕相當於察看當前cookie。