JSFiddle - React, Tailwind, and code Playground

HTML

<div class="input-prepend"><span class="focus-example1">
<span id="donate_wm" class="add-on">$</span>
					<input id="wm-pay-1" class="wm-pay-1" type="number" name="LMI_PAYMENT_AMOUNT" size="3" min="0" max="100" step="10" value="10" title="" data-original-title="Введите сумму">
</span></div>

<select id="wm-pay-2" class="wm-pay-2" name="LMI_PAYEE_PURSE" title="" style="min-width:30px;" data-original-title="Выбор валюты">
					<optgroup label="Выбор">	
							<option value="R">WMR</option>
							<option value="Z">WMZ</option>
							<option value="E">WME</option>
							<option value="U">WMU</option>
							<option value="B">WMB</option>
						</optgroup> 
				</select>

JavaScript

function donateChangeCurrency1( )
  {
    var selectionObj = document.getElementById( 'wm-pay-2' );
    var selection = selectionObj.value;
    var currencyObj = document.getElementById( 'donate_wm' );
    if( currencyObj )
    {
      var currencySymbols1 = { 'WMR': 'P','WMZ': '$', 'WME': '&euro;', 'WMU': '&#8372;', 'WMB': 'Br' };
      var currencySymbol = currencySymbols1[ selection ];
      currencyObj.innerHTML = currencySymbol;
    }
  }