<select id="choose-fruit>
　　<option value="1">Apple</option>
　　<option value="2">Orange</option>
　　<option value="3">Banana</option>
　</select>

　// Set option with value 'Orange' as selected
　document.querySelector('#choose-fruit').value = 'Orange';

　/ Set the option with index 2 as selected => Sets the 'Banana' option as selected
　document.querySelector('#choose-fruit').selectedIndex = 2;