单击按钮从表中选择前 5 个复选框

Question

我有一个看起来像这样的表：

<table id="start" class="appplytblclr">
    <tr class="heading">
        <td>First coumn</td>
        <td>second column</td>
        <td>3rd column</td>
        <td>4th column</td>
        <tr>
            <tr id='1'>
                <td>
                    <input type="checkbox" offval="no" value="&nbsp;">
                </td>
                <td>s</td>
                <td>t</td>
                <td>f</td>
            </tr>
            <tr id='2'>
                <td>
                    <input type="checkbox" offval="no" value="&nbsp;">
                </td>
                <td>s</td>
                <td>t</td>
                <td>f</td>
            </tr>
            <tr id='3'>
                <td>
                    <input type="checkbox" offval="no" value="&nbsp;">
                </td>
                <td>s</td>
                <td>t</td>
                <td>f</td>
            </tr>
            <tr id='4'>
                <td>
                    <input type="checkbox" offval="no" value="&nbsp;">
                </td>
                <td>s</td>
                <td>t</td>
                <td>f</td>
            </tr>
            <tr id='5'>
                <td>
                    <input type="checkbox" offval="no" value="&nbsp;">
                </td>
                <td>s</td>
                <td>t</td>
                <td>f</td>
            </tr>
            <tr id='6'>
                <td>
                    <input type="checkbox" offval="no" value="&nbsp;">
                </td>
                <td>s</td>
                <td>t</td>
                <td>f</td>
            </tr>
            <tr id='7'>
                <td>
                    <input type="checkbox" offval="no" value="&nbsp;">
                </td>
                <td>s</td>
                <td>t</td>
                <td>f</td>
            </tr>
    </tr>
</table>

我有一个按钮，单击该按钮后应选择前五个复选框。这是我到目前为止所尝试过的：

$('#clickbtn').on('click', function (e) {
    var sList = "";
    $('input[type=checkbox]').each(function () {
        sList += $(this).val() + ",";
    });
    var comma = sList.split(",", 5);
});

但它似乎不起作用。我应该如何解决这个问题？

Answer 1

您可以使用:lt()选择器：

$("#selectFirstFive").on("click", function() {
  var checkBoxes = $("#start tr td :checkbox:lt(5)");//using :lt get first 5 checkboxes
  $(checkBoxes).prop("checked", !checkBoxes.prop("checked"));//change checkbox status based on check/uncheck
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<table id="start" class="appplytblclr">
  <tr class="heading">
    <td>First coumn</td>
    <td>second column</td>
    <td>3rd column</td>
    <td>4th column</td>
    <tr>
      <tr id='1'>
        <td>
          <input type="checkbox" offval="no" value="&nbsp;">
        </td>
        <td>s</td>
        <td>t</td>
        <td>f</td>
      </tr>
      <tr id='2'>
        <td>
          <input type="checkbox" offval="no" value="&nbsp;">
        </td>
        <td>s</td>
        <td>t</td>
        <td>f</td>
      </tr>
      <tr id='3'>
        <td>
          <input type="checkbox" offval="no" value="&nbsp;">
        </td>
        <td>s</td>
        <td>t</td>
        <td>f</td>
      </tr>
      <tr id='4'>
        <td>
          <input type="checkbox" offval="no" value="&nbsp;">
        </td>
        <td>s</td>
        <td>t</td>
        <td>f</td>
      </tr>
      <tr id='5'>
        <td>
          <input type="checkbox" offval="no" value="&nbsp;">
        </td>
        <td>s</td>
        <td>t</td>
        <td>f</td>
      </tr>
      <tr id='6'>
        <td>
          <input type="checkbox" offval="no" value="&nbsp;">
        </td>
        <td>s</td>
        <td>t</td>
        <td>f</td>
      </tr>
      <tr id='7'>
        <td>
          <input type="checkbox" offval="no" value="&nbsp;">
        </td>
        <td>s</td>
        <td>t</td>
        <td>f</td>
      </tr>
</table>

<input type="button" id="selectFirstFive" value="select" />