Forget datalist element that good solution for autocomplete function, but not for combobox feature.
css:
.combobox {
display: inline-block;
position: relative;
}
.combobox select {
display: none;
position: absolute;
overflow-y: auto;
}
html:
<div class="combobox">
<input type="number" name="" value="" min="" max="" step=""/><br/>
<select size="3">
<option value="0"> 0</option>
<option value="25"> 25</option>
<option value="40"> 40</option>
</select>
</div>
js (jQuery):
$('.combobox').each(function() {
var
$input = $(this).find('input'),
$select = $(this).find('select');
function hideSelect() {
setTimeout(function() {
if (!$select.is(':focus') && !$input.is(':focus')) {
$select
.hide()
.css('z-index', 1);
}
}, 20);
}
$input
.focusin(function() {
if (!$select.is(':visible')) {
$select
.outerWidth($input.outerWidth())
.show()
.css('z-index', 100);
}
})
.focusout(hideSelect)
.on('input', function() {
$select.val('');
});
$select
.change(function() {
$input.val($select.val());
})
.focusout(hideSelect);
});
This works properly even when you use text input instead of number.