CSS/html display list in two columns if more than X amount of elements?

Question

I have a dynamic list of elements. I do not want this list to be too long. I could use:

ul {
    columns: 2;
    -webkit-columns: 2;
    -moz-columns: 2;
}

But this always results in two columns. I would prefer to only have one column if there are only a few elements in the list. So with 5 elements or less, I want this:

1
2
3
4
5

But with 6 or more elements I want this:

1    4
2    5
3    6

I use css3, html, bootstrap 2.3.2 and jquery Do anyone have some tips for the best way to do this?

Answer 1

If you are able to use CSS grid you can do this with grid-template-rows and grid-auto-flow directive. Grid can be used in most browsers natively and in IE11 with autoprefixer:

.list {
  display: grid;
  grid-template-rows: repeat(5, min-content);
  grid-auto-flow: column;
}

<ul class="list">
  <li class="item">1</li>
  <li class="item">2</li>
  <li class="item">3</li>
  <li class="item">4</li>
  <li class="item">5</li>
  <li class="item">6</li>
  <li class="item">7</li>
</ul>

Answer 2

You could simply filter ul element(s):

$('ul').filter(function(){
    return this.childNodes.length > 5
}).addClass('twoColumns');

ul.twoColumns {
  list-style: none;
    columns: 2;
    -webkit-columns: 2;
    -moz-columns: 2;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<ul>
    <li>1</li>
    <li>2</li>
    <li>3</li>
    <li>4</li>
    <li>5</li>
    <li>6</li>
</ul>