Javascript無法在Windows操作系統頁面之間檢索cookie

我正在使用TideSDK爲Windows開發桌面應用程序。我正在嘗試使用cookie來存儲用戶在登錄時輸入的電子郵件地址的信息。我保存的電子郵件地址（在我的index.html文件中）的cookie會在下一頁（mainMenu.html）加載時丟失。Javascript無法在Windows操作系統頁面之間檢索cookie

的index.html的Javascript：

//this is what I call when the login information is correct 



function setCookie(cname,cvalue,exdays) { 

      var d = new Date(); 
      d.setTime(d.getTime() + (exdays*24*60*60*1000)); 
      var expires = "expires=" + d.toGMTString(); 
      document.cookie = cname+"="+cvalue+"; "+expires; 

      } 

     function getCookie(cname) { 
     var name = cname + "="; 
     var ca = document.cookie.split(';'); 
     for(var i=0; i<ca.length; i++) { 
     var c = ca[i]; 
     while (c.charAt(0)==' ') c = c.substring(1); 
     if (c.indexOf(name) != -1) return c.substring(name.length, c.length); 
     } 
     return ""; 
     } 


     setCookie("email",em,30); //setting the cookie 

     window.location.href = "mainMenu.html"; // go to the next page

mainMenu.html的Javascript：

//this is what I call when the page gets loaded 

function getCookie(cname) { 
    var name = cname + "="; 
    var ca = document.cookie.split(';'); 
    for(var i=0; i<ca.length; i++) { 
     var c = ca[i]; 
     while (c.charAt(0)==' ') c = c.substring(1); 
     if (c.indexOf(name) != -1) return c.substring(name.length, c.length); 
    } 
    return ""; 
} 
    alert("email: "+getCookie("email"));

這是從我的mainMenu.html警報statment的樣子：

enter image description here