html全选和取消全选JS

<html>  
<body>  
  
    <table border="1">  
        <tr>  
            <th><input type="checkbox" onclick="swapCheck()" /></th>  
            <th>Month</th>  
            <th>Savings</th>  
        </tr>  
        <tr>  
            <td><input type="checkbox" /></td>  
            <td>January</td>  
            <td>$100</td>  
        </tr>  
        <tr>  
            <td><input type="checkbox" /></td>  
            <td>February</td>  
            <td>$150</td>  
        </tr>  
    </table>  
  
    <script type="text/javascript"  
        src="http://apps.bdimg.com/libs/jquery/2.1.1/jquery.min.js"></script>  
  
    <script type="text/javascript">  
        //checkbox 全选/取消全选  
        var isCheckAll = false;  
        function swapCheck() {  
            if (isCheckAll) {  
                $("input[type='checkbox']").each(function() {  
                    this.checked = false;  
                });  
                isCheckAll = false;  
            } else {  
                $("input[type='checkbox']").each(function() {  
                    this.checked = true;  
                });  
                isCheckAll = true;  
            }  
        }  
    </script>  
  
</body>  
</html>
效果图：
html全选和取消全选JS