html5中localStorage存储

以下代码实现了增、删，改，差（缺点是localStorage只有5MB的大小，不允许大数据量的存储） 且localStorage对象仅依赖于浏览器，2个不同的浏览器之间是不允许交互的。

 <ul id="ulMessage"></ul>
    <div>
        学号:<input type="text" id="txt_xh" />
        姓名:<input type="text" id="txt_name" />
        分数:<input type="text" id="txt_fenshu" />
        <input type="button" value="保存" οnclick="javascript: savedata();" />
        <input type="button" value="清空" οnclick="javascript: localStorage.clear();" />
    </div>

        function $$(id) {
            return document.getElementById(id);
        }
        function savedata() {
            var setdata = new Object();
            setdata.id = $$("txt_xh").value;
            setdata.name = $$("txt_name").value;
            setdata.fenshu = $$("txt_fenshu").value;
            localStorage.setItem($$("txt_xh").value, JSON.stringify(setdata));
            initData();
            $$("txt_xh").value = "";
            $$("txt_name").value = "";
            $$("txt_fenshu").value = "";
        }
        function initData() {
            //初始化数据
            var tempstr = "";
            tempstr = "<table width='80%'>";
            tempstr += "<tr><td width='30%'>学号</td> <td width='30%'>姓名</td> <td width='30%'>分数</td><TD>修改</td><TD>删除</td></tr>"
            //alert(localStorage.length);
            for (var k = 0; k < localStorage.length; k++) {
                //alert(localStorage.key(k));
                var item = JSON.parse(localStorage.getItem(localStorage.key(k)));
                tempstr += "<tr>";
                tempstr += "<td width='30%'>" + item.id + "</td>    ";
                tempstr += "<td width='30%'>" + item.name + "</td>  ";
                tempstr += "<td width='30%'>" + item.fenshu + "</td>";
                tempstr += "<TD><a href='javascript:void(0)' οnclick='edit("+k+")'>修改</a></td>";
                tempstr += "<TD><a href='javascript:void(0)' οnclick='del(" + k + ")'>删除</a></td>";
                tempstr += "</tr>";
            }
            tempstr += "</table>";
            $$("ulMessage").innerHTML = tempstr;
        }
        function edit(k)
        {
            if (k < localStorage.length)
            {
                var item = JSON.parse(localStorage.getItem(localStorage.key(k)));
                $$("txt_xh").value = item.id;
                $$("txt_name").value = item.name;
                $$("txt_fenshu").value = item.fenshu;
            }
        }
        function del(k)
        {
            if (k < localStorage.length)
            {
                var key = localStorage.key(k);
                //alert(key);
                localStorage.removeItem(key);
                initData();
            }

        }