html - Editable 'Select' element

Question

I would like to have a select element in the form but besides the options in the dropdown, it would be useful to be able to edit it and add new option but not with another input text, I need all in once. Is it possible?

Answer 1

Nothing is impossible. Here's a solution that simply sets the value of a text input whenever the value of the <select> changes (rendering has been tested on Firefox and Google Chrome):

.select-editable {position:relative; background-color:white; border:solid grey 1px;  width:120px; height:18px;}
.select-editable select {position:absolute; top:0px; left:0px; font-size:14px; border:none; width:120px; margin:0;}
.select-editable input {position:absolute; top:0px; left:0px; width:100px; padding:1px; font-size:12px; border:none;}
.select-editable select:focus, .select-editable input:focus {outline:none;}

<div class="select-editable">
  <select onchange="this.nextElementSibling.value=this.value">
    <option value=""></option>
    <option value="115x175 mm">115x175 mm</option>
    <option value="120x160 mm">120x160 mm</option>
    <option value="120x287 mm">120x287 mm</option>
  </select>
  <input type="text" name="format" value=""/>
</div>