全选与反选

代码：

<div>
    <input type="button" value="添加主机" onclick="show();" />
    <input type="button" value="全选" onclick="all01();" />
    <input type="button" value="取消" onclick="cancel();" />
    <input type="button" value="反选" onclick="reverse();" />
    
    <table>
        <thead>
        <tr>
            <th>选择</th>
            <th>主机名</th>
            <th>端口</th>
        </tr>
        </thead>
        <tbody id="tb">
        <tr>
            <td><input type="checkbox" /></td>
            <td>127.0.0.1</td>
            <td>80</td>
        </tr>
        <tr>
            <td><input type="checkbox" /></td>
            <td>192.168.1.11</td>
            <td>8080</td>
        </tr>
        <tr>
            <td><input type="checkbox" /></td>
            <td>10.17.32.12</td>
            <td>8088</td>
        </tr>
        </tbody>
    </table>
    <!--灰幕-->
    <div class="c1 hide" id="i1">
    </div>
    <!--弹出框-->
    <div class="c2 hide" id="i2">
    <input type="text" /><br />
    <input type="text" />
    <div>
    <input type="button" value="取消"  onclick="hide();"/>
    <input type="button" value="确定" />
    </div>
    </div>
    </div>
    
    <script>
        function all01(){
            
            var tbody = document.getElementById('tb');
            var tr_list = tbody.children;
            for(var i=0;i<tr_list.length;i++){
                var current_tr = tr_list[i];
                var checkbox = current_tr.children[0].children[0];
                checkbox.checked = true;
            }
        }
        function cancel(){
            
            var tbody = document.getElementById('tb');
            var tr_list = tbody.children;
            for(var i=0;i<tr_list.length;i++){
                var current_tr = tr_list[i];
                var checkbox = current_tr.children[0].children[0];
                checkbox.checked = false;
            }
        }
        function reverse(){
            
            var tbody = document.getElementById('tb');
            var tr_list = tbody.children;
            for(var i=0;i<tr_list.length;i++){
                var current_tr = tr_list[i];
                var checkbox = current_tr.children[0].children[0];
            
            if (checkbox.checked){
                checkbox.checked=false;
            }else{
                checkbox.checked=true;
            }
            }
        }
    </script>