JSFiddle - React, Tailwind, and code Playground
by nikolya223
HTML
<div class="cont1" style="text-align: center;">
<div class="input-prepend"><span class="focus-example1">
<span id="donate_wm" class="add-on">WMR</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="Введите сумму" />
</span></div>
<span class="focus-example">
<select id="wm-pay-2" class="wm-pay-2" name="LMI_PAYEE_PURSE" title="Выбор валюты" style="min-width:30px;">
<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>
</span>
JavaScript
$("select").on("change",function () {
var str = $("#wm-pay-2 option:selected").text().trim();
$("#donate_wm").text(str);
}).trigger('change');