<select id="cur">
  <option value="en">Dollar</option>
  <option value="eu">Euro</option>
  <option value="ru">Ruble</option>
  <option value="sh">Shekel</option>
</select>

<select id="amount"></select>
function updateDependent(){
  var c = $currencySelect.val(),
      s = master[c].symbol,
      vals = master[c].values;

  $amountSelect.empty();
  $.each(vals, function(){
    $('<option/>', { value : this }).text(s + this).appendTo($amountSelect);
  });
}

//var subDomain = window.location.host.split('.')[0] || "ru",

var subDomain = "ru",
  master = {
    "en": {
      "symbol": "$",
      "values": [10, 20, 30]
    },
    "eu": {
      "symbol": "€",
      "values": [12, 45, 49]
    },
    "ru": {
      "symbol": "",
      "values": [454, 489, 877]
    },
    "sh": {
      "symbol": "",
      "values": [30, 50, 100]
    }
  },
  $currencySelect = $("#cur"),
  $amountSelect = $("#amount");

$currencySelect.on("change", updateDependent);
$currencySelect.val(subDomain).trigger("change");
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External JavaScript

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