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web存储

localStorage 对象存储的数据没有时间限制。数据以 键/值 对存在, web网页的数据只允许该网页访问使用。

  • 保存数据:localStorage.setItem(key,value);

  • 读取数据:localStorage.getItem(key);

  • 删除单个数据:localStorage.removeItem(key);

  • 删除所有数据:localStorage.clear();

  • 得到某个索引的key:localStorage.key(index);

将用户名和密码保存到localstorage中,在页面展示

<!DOCTYPE html><html>
    <head>
        <meta charset="UTF-8">
        <title></title>
        <style>
            td {text-align: center;}
        </style>
    </head>
    <body>
        <label for="">用户名:</label><input type="text" id="username" /><br>
        <label for="">密&emsp;码:</label><input type="password" id="password" /><br>
        <button  onclick="btn()">保存</button><button onclick="del()">清空用户信息</button>
        <div id="table-box" style="display: none;">
            <table border="1" cellpadding="0" cellspacing="0" id="table" width="300" >
                <caption>用户信息表</caption>
                <tr>
                    <th>序号</th>
                    <th>用户名</th>
                    <th>密码</th>
                    <th>操作</th>
                </tr>
            </table>
        </div>
        <script>
            window.onload = function() { //读取缓存
                var str = "";                var Text = localStorage.getItem("T");
                Text = JSON.parse(Text); //把字符串转换成JSON对象
                if(Text != null) { //localStorage不为空
                    show()                    var objs = Text.te;                    for(var i = 0; i < objs.length; i++) {
                        str += "<tr><td>" + (i + 1) + "</td><td>" + objs[i].name + "</td><td>" + objs[i].pd + "</td><td><button onclick=‘del_one("+objs[i].name+")‘>删除</button></td></tr>";
                    }
                    document.getElementById("table").innerHTML += str;
                }
            }            function btn() { //存入缓存
                var u = document.getElementById("username").value;                var b = document.getElementById("password").value;                if(u != ‘‘ && b != ‘‘) {
                    add(u, b)
                }
            }            function add(a, b) { //设置缓存
                var Save = false;                var Index = table.rows.length;                var Text = localStorage.getItem("T");
                Text = JSON.parse(Text); //将一个 JSON 字符串转换为对象。
                if(Text != null && Text != "underfind") {                    var objs = Text.te;                    for(var i = 0; i < objs.length; i++) { //遍历缓存
                        Save = false;                        if(objs[i].name == a) { //统计缓存中相同数据个数
                            alert("用户名已存在")
                            Save = true;                            break;
                        }
                    }                    if(!Save) {  //如果条件为真,则执行
                        var str = "<tr><td>" + (Index) + "</td><td>" + a + "</td><td>" + b + "</td><td><button onclick=‘del_one("+a+")‘>删除</button></td></tr>";
                        document.getElementById("table").innerHTML += str;
                        objs[objs.length] = {
                            num: Index,
                            name: a,
                            pd: b
                        };
                    }
                } else {
                    show()                    var str = "<tr><td>" + (Index) + "</td><td>" + a + "</td><td>" + b + "</td><td><button onclick=‘del_one("+a+")‘>删除</button></td></tr>";
                    document.getElementById("table").innerHTML += str;                    var Text = { //要存储的JSON对象
                        te: [{
                            num: Index,
                            name: a,
                            pd: b
                        }]
                    }
                }
                Text = JSON.stringify(Text); //将JSON对象转化成字符串
                localStorage.setItem("T", Text); //用localStorage保存转化好的的字符串
                document.getElementById("username").value = ‘‘;
                document.getElementById("password").value = ‘‘;
            }            function del() { //清空缓存
                localStorage.clear();
                window.location.reload();
            }            function show(){
                document.getElementById("table-box").style.display ="block";
            }            function del_one(event){
                var Text = localStorage.getItem("T"); 
                Text = JSON.parse(Text); //把字符串转换成JSON对象
                var objs = Text.te;                for(var i = 0; i < objs.length; i++) {                    if(objs[i].name == event) { //说明存在该用户
                        objs.splice(i, 1); //删除某一条数据
                        Text = JSON.stringify(Text); //将JSON对象转化成字符串
                        localStorage.setItem("T", Text); //用localStorage保存转化好的的字符串
                    }
                }                if(objs.length == "0"){localStorage.clear();}
                window.location.reload();
            }        </script>
    </body></html>


web存储