Question

我试图将cookie的值转换为全局变量，然后我可以使用document.getElementById将其放入div中。

这是我的代码 - 它完全按照它记住cookie的事实运作，但它只是不会做一行，我已经清楚地概述了你的评论。

这是我的所有代码......

<!DOCTYPE HTML>
<html>
<head>
    <script>
        var globalVar = "";

        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) == 0) {
                    return c.substring(name.length, c.length);
                }
            }
            return "";
        }

        function checkCookie() {
            var user = getCookie("username");
            if (user != "") {
                alert("Welcome again " + user);
                globalVar = getCookie("username");
                document.getElementById("demo").innerHTML = globalVar; /* THIS LINE DON'T WORK WHY NOT! THE ONE BELOW DOES IN THE CHANGE COOKIE FUNCTION DOES! */
            } else {
                user = prompt("Please enter your name:", "");
                if (user != "" && user != null) {
                    setCookie("username", user, 30);
                }
            }
        }

        function changeCookie() {
            var user = getCookie("username");
            user = prompt("Please enter your name:", "");
            if (user != "" && user != null) {
                setCookie("username", user, 30);
            }
            document.getElementById("demo").innerHTML = user; /* THIS WORKS! */
        }
        checkCookie();
    </script>
</head>
<body>
    <div id="demo"></div>
    <button onclick="changeCookie()">Change username</button>
</body>
</html>

Answer 1

尝试在页面加载完成后立即调用checkCookie()。

<body onload="checkCookie()">

另一种方法是将脚本标记移动到页面的末尾，就在body的结束标记之前，如下所示：

<html>
<body>
   <div id="demo"></div>
   <button></button>

  <!-- the rest of the page's HTML here -->

   <script>
      ....
      .... your script code here
      ....
      ....
      checkCookie();
   </scirpt>
</body>
</html>

Answer 2

您只是在案例陈述的第一部分中将html分配到"demo"，您需要将其添加到第二部分，并分配user变量，而不是globalVar 。也可以按照其他答案中的建议将代码放在正文的末尾。

function checkCookie() {
    var user = getCookie("username");
    if (user != "") {
        alert("Welcome again " + user);
        globalVar = getCookie("username");
        document.getElementById("demo").innerHTML = globalVar; 
    } else {
       user = prompt("Please enter your name:","");
       if (user != "" && user != null) {
           setCookie("username", user, 30);
           document.getElementById("demo").innerHTML = user;
       }
    }
}

为什么我不能将cookie输入变量然后为结果分配div？

2 个答案: