Javascript: adding options to select dynamically

Your html:


<select id="estadosiniciales">
                    <option value ="sydney">Sydney</option>
                    <option value ="melbourne">Melbourne</option>
                    <option value ="cromwell" selected>Cromwell</option>
                    <option value ="queenstown">Queenstown</option>
</select>

Your Javascript:


var newOption = new Option("newStateName","newStateName");
var selectIni = $("#estadosiniciales"); // using Jquery
selectIni.append(newOption)


Resources:
http://www.devguru.com/technologies/ecmascript/quickref/option.html
http://stackoverflow.com/questions/4647863/trouble-dynamically-adding-options-to-select