jquery - 鼠标悬停在多个 td rowspan

Question

我有一个包含多个 td rowspan 的表。在鼠标悬停时，整个字母表行应变为红色。例如，如果我们将鼠标放在任何字母值上，整个字母部分应该显示为红色。数字也是如此。

我尝试了一些 jQuery 来实现这一点，但无法获得相同颜色的整行字母或数字。

$("td").hover(function() {
  $el = $(this);
  $el.parent().addClass("hover");

  if ($el.parent().has('td[rowspan]').length == 0) {
    $el
      .parent()
      .prevAll('tr:has(td[rowspan]):first')
      .find('td[rowspan]')
      .addClass("hover");
  }
}, function() {
  $el
    .parent()
    .removeClass("hover")
    .prevAll('tr:has(td[rowspan]):first')
    .find('td[rowspan]')
    .removeClass("hover");
});

body {
  padding: 50px;
}

table {
  width: 100%;
  border-collapse: collapse;
}

td,
th {
  padding: 20px;
  border: 1px solid black;
}

.hover {
  background: red;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<table>
  <tbody>
    <tr>
      <td rowspan="3">Alphabet</td>
      <td rowspan="2">a</td>
      <td>b</td>
      <td>c</td>
    </tr>
    <tr>
      <td>d</td>
      <td>e</td>
    </tr>
    <tr>
      <td>f</td>
      <td>g</td>
      <td>h</td>
    </tr>
    <tr>
      <td rowspan="3">Number</td>
      <td>1</td>
      <td>2</td>
      <td>3</td>
    </tr>
    <tr>
      <td>4</td>
      <td>5</td>
      <td>6</td>
    </tr>
    <tr>
      <td>7</td>
      <td>8</td>
      <td>9</td>
    </tr>
  </tbody>
</table>

我们如何解决这个问题？

Answer 1

编辑:添加了一种查找每个 block 顶部的方法。

编辑 2 - 预先做好艰苦的工作 再次考虑这个问题，最好在开始时计算出每个 block 中有哪些行并将该列表与每一行一起存储，例如每个字母行存储对包含第 1-4 行的数组的引用。因此，当您悬停时，您只需要获取存储在父行中的行数组并将该类应用到这些行。

通过检查 block 顶行的最大行跨度，您不仅限于检查第一个单元格。在更新后的代码中，我将字母表移到了中间以演示这一点，并添加了几个其他 block 来演示单行 block 的工作原理。

function findBlocks(theTable) {
    if ($(theTable).data('hasblockrows') == null) {
        console.log('findBlocks'); // to prove we only run this once

        // we will loop through the rows but skip the ones not in a block
        var rows = $(theTable).find('tr');
        for (var i = 0; i < rows.length;) {

            var firstRow = rows[i];

            // find max rowspan in this row - this represents the size of the block
            var maxRowspan = 1;
            $(firstRow).find('td').each(function () {
                var attr = parseInt($(this).attr('rowspan') || '1', 10)
                if (attr > maxRowspan) maxRowspan = attr;
            });

            // set to the index in rows we want to go up to
            maxRowspan += i;

            // build up an array and store with each row in this block
            // this is still memory-efficient, as we are just storing a pointer to the same array
            // ... which is also nice becuase we can build the array up in the same loop
            var blockRows = [];
            for (; i < maxRowspan; i++) {
                $(rows[i]).data('blockrows', blockRows);
                blockRows.push(rows[i]);
            }

            // i is now the start of the next block
        }

        // set data against table so we know it has been inited (for if we call it in the hover event)
        $(theTable).data('hasblockrows', 1);
    }
}

$("td").hover(function () {
    $el = $(this);
    //findBlocks($el.closest('table')); // you can call it here or onload as below
    $.each($el.parent().data('blockrows'), function () {
        $(this).find('td').addClass('hover');
    });
}, function () {
    $el = $(this);
    $.each($el.parent().data('blockrows'), function () {
        $(this).find('td').removeClass('hover');
    });
});

findBlocks($('table'));

body {
    padding: 50px;
}
table {
    width: 100%;
    border-collapse: collapse;
}
td, th {
    padding: 20px;
    border: 1px solid black;
}
.hover {
    background: red;
}

<table>
    <tbody>
        <tr>
            <td>Symbols</td>
            <td>+</td>
            <td>-</td>
            <td>*</td>
        </tr>
        <tr>
            <td rowspan="2">a</td>
            <td>b</td>
            <td rowspan="4">Alphabet</td>
            <td>c</td>
        </tr>
        <tr>
            <td>d</td>
            <td>e</td>
        </tr>
        <tr>
            <td rowspan="2">f</td>
            <td>g</td>
            <td>h</td>
        </tr>
        <tr>
            <td>i</td>
            <td>j</td>
        </tr>
        <tr>
            <td>Bitwise</td>
            <td>&amp;</td>
            <td>|</td>
            <td>^</td>
        </tr>
        <tr>
            <td rowspan="3">Number</td>
            <td>1</td>
            <td>2</td>
            <td>3</td>
        </tr>
        <tr>
            <td>4</td>
            <td>5</td>
            <td>6</td>
        </tr>
        <tr>
            <td>7</td>
            <td>8</td>
            <td>9</td>
        </tr>
    </tbody>
</table>

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