change select elemet option with javascript : hi i search it  a lot and no code work for this problem .
i have a select element 

   

<!-- begin snippet: js hide: false console: true babel: false -->

<!-- language: lang-js -->

    $(document).ready(function(){
    $('#clientbutton').click(function(e) {
     $("input#citycode").value(example :2);
     }

<!-- language: lang-html -->

    <select id="citycode">
        <option value="1">city 1</option>
        <option value="2">city 2</option>
        <option value="3">city 3</option>
        </select>

<!-- end snippet -->

but i cant change it with java script on the client side. i try many other solution in stackoverflow but none of them work