update

Author: jpuri

ui/pages/confirmations/components/confirm/info/typed-sign/permit-simulation/permit-simulation.tsx

@@ -55,8 +55,6 @@ const PermitSimulation: React.FC<{
   const { tokenValue, tokenValueMaxPrecision } = useMemo(() => {
     const tokenAmount = calcTokenAmount(value, tokenDecimals);
 
-    // FIXME - Precision may be lost for large values when using formatAmount
-    /** @see {@link https://github.com/MetaMask/metamask-extension/issues/25755} */
     return {
       tokenValue: formatAmount('en-US', tokenAmount),
       tokenValueMaxPrecision: formatAmountMaxPrecision('en-US', tokenAmount),

ui/pages/confirmations/components/simulation-details/formatAmount.ts

@@ -81,8 +81,14 @@ export function formatAmount(locale: string, amount: BigNumber): string {
   );
 
   if (maximumFractionDigits === 0) {
-    // No decimals to display – we can use BigInt to localize without loss of precision.
-    return BigInt(amount.toFixed(0)).toLocaleString(locale);
+    return new Intl.NumberFormat(locale, {
+      maximumFractionDigits,
+    } as Intl.NumberFormatOptions).format(
+      // string is valid parameter for format function
+      // for some reason it gives TS issue
+      // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/NumberFormat/format#number
+      amount.toFixed(maximumFractionDigits) as unknown as number,
+    );
   }
 
   // At most 4 (MAX_SIGNIFICANT_DECIMAL_PLACES + 1) significant digits – Use Intl.NumberFormat to localize