[ruslan_mart]

<form name="myForm">
   <label for="kiev"><input type="radio" name="city" value="1" id="kiev">Київ</label>

   <label for="charkiw"><input type="radio" name="city" value="2" id="charkiw">Харків</label>

   <label for="odessa"><input type="radio" name="city" value="3" id="odessa">Одесса</label>
</form>

var form = document.forms.myForm;
var city = form.querySelector('[name="city"][value="' + form.elements.city.value + '"]');