JSFiddle - React, Tailwind, and code Playground

by Vitaliy T

HTML

<select id="country" name="country">
  <option  id="1"  value="RU">Россия</option>
  <option  id="2"  value="KZ">Казахстан</option>
  <option  id="3" value="BY">Беларусь</option>
</select>
<input name="price" id="price" value="11">

JavaScript

let _vals = {
	id_1 : 11,
  id_2 : 12,
  id_3 : 13
}; 

$('select[name="country"]').on('change', function(){
let _s = $(this);
let _v = $(_s).find('option:selected').attr('id');

$('input[name="price"]').val(_vals['id_'+_v]);

});