user1114864 user1114864 - 6 months ago 34
CSS Question

How to get a Bootstrap dropdown submenu to 'dropup'

I have a Bootstrap dropdown menu. The last 'li' item is a submenu. How do I get the submenu to dropup while the full menu drops down? Here's the code:

<div class="dropdown">
<a class="inputBarA dropdown-toggle" data-toggle="dropdown" href="#">FILTER</a>
<ul class="dropdown-menu" role="menu" aria-labelledby="dLabel">
<li role="presentation">
<a role="menuitem" href="#">Text</a>
</li>
<li role="presentation">
<label>Label name</label>
<label>Label name</label>
<label class="checkbox">
<input type="checkbox">
Text </label>
<label class="checkbox">
<input type="checkbox">
Text </label>
<label class="checkbox">
<input type="checkbox">
Text </label>
<label class="checkbox">
<input type="checkbox">
Text </label>
</li>
<li class="dropdown-submenu">
<a tabindex="-1" href="#">Centralities</a>
<ul class="dropdown-menu">
<label class="radio">
<input type="radio" name="options" id="optionsRadios1" value="A" checked>
AA </label>
<label class="radio">
<input type="radio" name="options" id="optionsRadios2" value="B">
BB </label><label class="radio">
<input type="radio" name="options" id="optionsRadios2" value="C">
CC </label><label class="radio">
<input type="radio" name="options" id="optionsRadios2" value="D">
DD </label><label class="radio">
<input type="radio" name="options" id="optionsRadios2" value="E">
EE </label>
</ul>
</li>
</ul>
</div>

Answer

It sounds like the answer below would be how to do it from scratch, I was unaware there was a dropup class in Bootstrap...

So the short Bootstrap answer is to apply the class "dropup" to the <ul> in earlier versions of bootstrap:

 <ul class="dropdown-menu dropup" role="menu" aria-labelledby="dLabel">

However in newer versions of bootstrap (v3) the "dropup" class needs to be applied to the <ul>'s container instead of the the <ul> itself:

<div class="dropup">
    <ul class="dropdown-menu" role="menu" aria-labelledby="dLabel">
</div>

See http://jsfiddle.net/ZgyZP/5/

Original working answer that doesn't use bootstrap:

You could use javascript to calculate the height of the submenu and then negatively offset the submenu's position.

something like (with jQuery):

$('.dropdown-submenu').hover(
    function(){
    //hover in 
        $('.dropdown-submenu > ul').css('top', '-' + $('.dropdown-submenu > ul').css('height'));

    },
    //hover out
    function(){
    }
);

Fiddle: http://jsfiddle.net/ZgyZP/4/

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