Javascript firefox中的本地存储密钥验证失败

我试图根据本地存储中存在的特定密钥生成html内容。代码如下：

    // Check if the user is signed in or not
    if(localStorage.getItem("token") === null) {
        document.getElementById("main").innerHTML = document.getElementById("welcomeview").innerHTML;
    } else {
        document.getElementById("main").innerHTML = document.getElementById("profileview").innerHTML;
    }

即使本地存储中未设置令牌密钥，也始终显示纵断面图：

localStorage
Storage { token: "undefined", length: 1 }

为什么?

编辑：

正在使用AJAX请求的响应值设置令牌：

function sign_in() {

        var uri, method, formId, $form, form_data;

        uri = location.protocol + '//' + location.host + "/sign_in";
        method = "POST";
        formId = "#signin_form_id";

        $form = $(formId);
        form_data = get_form_data($form);

        // Set-up ajax call
        var request = {
            url: uri,
            type: method,
            contentType: "application/json",
            accepts: "application/json",
            cache: false,
            dataType: 'json',
            data: form_data
        };
        // Make the request
        $.ajax(request).done(function(data) { // Handle the response
            // Attributes are retrieved as object.attribute_name
            // alert(obj.count);
            if(data.successSignIn === false) {
                // Login failed we show the welcome page
                alert(data.message);
                document.getElementById("main").innerHTML = document.getElementById("welcomeview").innerHTML;
            } else {
                // Login succeeded. We load the user's info, his messages and also a form in which he can type messages
                // Save the token received from the server. Could also be stored as a cookie
                localStorage.setItem('token', data.token);
                // Go to the home page
                go_home();
            }
        }).fail(function(jqXHR, textStatus, errorThrown) {
                    console.log(JSON.stringify(jqXHR));
                    console.log("AJAX error: " + textStatus + ' : ' + errorThrown);
                }
        );
        location.reload();

}

---

已编辑：对设置项

localStorage.setItem（“token”，typeof undefined==data.token？undefined:data.token）尝试此操作。

。避免使用字符串

“未定义”

我建议：

1） 替换为

if（localStorage.getItem（“token”）{…}

3） 此外，您还可以通过三元运算符进行示例

var welcomeText = document.getElementById("welcomeview").innerHTML, 
profileText = document.getElementById("profileview").innerHTML;

document.getElementById("main").innerHTML = (localStorage.getItem("token")) ? welcomeText : profileText 

---

如果

“undefined”==null

始终为false，则永远不会进入

部分

在您的情况下，您需要检查
if（localStorage.getItem（“token”）==“undefined”）
。
令牌键已设置并且是字符串
“undefined”
只需替换
if（localStorage.getItem（“token”）{…}
您也可以尝试if（localStorage中的“token”）{…}如何添加/删除密钥？删除密钥的正确方法localStorage.removeItem（密钥）；