css - How to animate toggling of table rows?

Question

I want to animate the appearance and disappearance of table rows.

First of all I tried using a CSS transition, but it did nothing due to the change of the display property.

So I used an animation, which works as expected.

The problem is, the full height of the row is reserved when the animation begins. See the snippet below for an illustration of the problem: Row 3 is pushed down straight away, before the animation begins.

How can I animate the height of the row progressively, so that it only takes as much space as needed?

And as a bonus:

• it should not require a fixed height for rows
• it should appear as a translation, rather than a scaling; it should look like it's sliding from the bottom of the row above it
• it should be bidirectional (do the opposite when I hide it)

$('button').on('click', function() {
  $('tr:nth-child(2)').toggleClass('active');
});

@keyframes anim {
  0% {
    transform: scaleY(0);
  }
  100% {
    transform: scaleY(1);
  }
}
tr {
  background: #eee;
  border-bottom: 1px solid #ddd;
  display: none;
  transform-origin: top;
}
tr.active {
  display: table-row;
  animation: anim 0.5s ease;
}
td {
  padding: 10px;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.0.2/jquery.min.js"></script>
<button type="button">Toggle</button>
<table>
  <tbody>
    <tr class="active">
      <td>Row 1</td>
      <td>...</td>
      <td>...</td>
    </tr>
    <tr>
      <td>Row 2</td>
      <td>...</td>
      <td>...</td>
    </tr>
    <tr class="active">
      <td>Row 3</td>
      <td>...</td>
      <td>...</td>
    </tr>
  </tbody>
</table>

Answer 1

As table row/cell don't respect a height smaller than its content we need to use an inner div, we can't animate display and we can't animate a height set to auto, so I here show a solution using max-height.

The trick is to give max-height a value high enough to enable the highest content.

$('button').on('click', function() {
  $('tr:nth-child(2)').toggleClass('active');
});

table {
  border-collapse: collapse;
}
tr {
  background: #eee;
  border-bottom: 1px solid #fff;
}
tr, td {
  padding: 0;
}
tr td div {
  max-height: 0;
  padding: 0 10px;
  box-sizing: border-box;
  overflow: hidden;
  transition: max-height 0.3s, padding 0.3s;
}
tr.active td div {
  max-height: 100px;
  padding: 10px 10px;
  transition: max-height 0.6s, padding 0.6s;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.0.2/jquery.min.js"></script>
<button type="button">Toggle</button>
<table>
  <tbody>
    <tr class="active">
      <td><div>Row 1</div></td>
      <td><div>...</div></td>
      <td><div>...</div></td>
    </tr>
    <tr>
      <td><div>Row 2</div></td>
      <td><div>...</div></td>
      <td><div>...</div></td>
    </tr>
    <tr class="active">
      <td><div>Row 3</div></td>
      <td><div>...</div></td>
      <td><div>...</div></td>
    </tr>
  </tbody>
</table>