JS中localStorage和sessionStorage的用法及区别

<script type="text/javascript">
    //定义json格式字符串
    var userData = {
        name:"Caideyang",
        account:"sankyu",
        level:1,
        disabled:true
    };
    //存储userData数据
    //sessionStorage存储数据的语法跟localStorage相同，
    //sessionStorage存储的数据的生命周期为只保存在设置session的当前窗口和当前窗口新建的新窗口，知道相关联的窗口关闭而失效；
    //localStorage则能永久存储直到浏览器卸载或者人为去清除
    localStorage.setItem("userData",JSON.stringify(userData));
    //读取userData数据并赋值给新变量
    var newUserData = JSON.parse(localStorage.getItem("userData"));
    //删除本地存储的item
    //localStorage.removeItem("userData");
    //输出对象里存储的数据 
    /*alert(newUserData.name);
    alert(newUserData.level);*/
    //无法通过点语法直接修改localStorage中的值，
    JSON.parse(localStorage.getItem("userData")).name = "Chengwanqing";
    userData.name = "Caijincheng";
    alert(userData.name);
    //localStorage存储的数据未被改变
    alert(JSON.parse(localStorage.getItem("userData")).name);

</script>