extract exchange amount validation

src/services/exchangeAmount.js

@@ -0,0 +1,9 @@
+const MAX_EXCHANGE_AMOUNT = 1e12;
+
+export function validateExchangeAmount(value) {
+  if (value === null || value === undefined || (typeof value === 'string' && !value.trim())) return false;
+  const amount = Number(value);
+  return Number.isFinite(amount) && amount >= 0 && amount <= MAX_EXCHANGE_AMOUNT;
+}
+
+export { MAX_EXCHANGE_AMOUNT };