From a652e40a2dbb927a115abc3b40700d0d313a5215 Mon Sep 17 00:00:00 2001
From: Sam Zhou <samzhou19815@meta.com>
Date: Wed, 4 Nov 2026 07:47:36 -0800
Subject: [PATCH] Make the conversions of `parseInt` and `isNaN` explicit

Summary:
TypeScript declares `parseInt(string: string, radix?: number)` and `isNaN(number: number)`, and Flow is adopting the same signatures. Calls that pass another type rely on the function's implicit conversion and start to error.

Wrap each such argument in `String(...)` (`parseInt`) or `Number(...)` (`isNaN`), the conversion the function already applies, so behavior doesn't change. The calls were found from Flow's errors and rewritten by a codemod. 8 arguments in 6 files in React Native and Metro.

Changelog: [Internal]

Differential Revision: D129644365
---
 .../src/generators/components/CppHelpers.js                   | 4 ++--
 .../Libraries/LogBox/UI/LogBoxInspectorStackFrame.js          | 2 +-
 .../react-native/Libraries/StyleSheet/processTransform.js     | 2 +-
 .../js/examples/SectionList/SectionList-scrollable.js         | 2 +-
 packages/rn-tester/js/examples/XHR/XHRExampleDownload.js      | 2 +-
 5 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/packages/react-native-codegen/src/generators/components/CppHelpers.js b/packages/react-native-codegen/src/generators/components/CppHelpers.js
index 6a64b2eab3a9..aa352c4b56f4 100644
--- a/packages/react-native-codegen/src/generators/components/CppHelpers.js
+++ b/packages/react-native-codegen/src/generators/components/CppHelpers.js
@@ -215,7 +215,7 @@ function convertDefaultTypeToString(
       return String(typeAnnotation.default);
     case 'DoubleTypeAnnotation':
       const defaultDoubleVal = typeAnnotation.default;
-      return parseInt(defaultDoubleVal, 10) === defaultDoubleVal
+      return parseInt(String(defaultDoubleVal), 10) === defaultDoubleVal
         ? typeAnnotation.default.toFixed(1)
         : String(typeAnnotation.default);
     case 'FloatTypeAnnotation':
@@ -223,7 +223,7 @@ function convertDefaultTypeToString(
       if (defaultFloatVal == null) {
         return '';
       }
-      return parseInt(defaultFloatVal, 10) === defaultFloatVal
+      return parseInt(String(defaultFloatVal), 10) === defaultFloatVal
         ? defaultFloatVal.toFixed(1)
         : String(typeAnnotation.default);
     case 'ReservedPropTypeAnnotation':
diff --git a/packages/react-native/Libraries/LogBox/UI/LogBoxInspectorStackFrame.js b/packages/react-native/Libraries/LogBox/UI/LogBoxInspectorStackFrame.js
index e7b75d9b4f1e..e8eb47de8c12 100644
--- a/packages/react-native/Libraries/LogBox/UI/LogBoxInspectorStackFrame.js
+++ b/packages/react-native/Libraries/LogBox/UI/LogBoxInspectorStackFrame.js
@@ -25,7 +25,7 @@ component LogBoxInspectorStackFrame(
   frame: StackFrame,
   onPress?: ?(event: GestureResponderEvent) => void,
 ) {
-  const column = frame.column != null && parseInt(frame.column, 10);
+  const column = frame.column != null && parseInt(String(frame.column), 10);
   const location =
     getFileName(frame.file) +
     (frame.lineNumber != null
diff --git a/packages/react-native/Libraries/StyleSheet/processTransform.js b/packages/react-native/Libraries/StyleSheet/processTransform.js
index 6715d05c9d17..565e6aca8bed 100644
--- a/packages/react-native/Libraries/StyleSheet/processTransform.js
+++ b/packages/react-native/Libraries/StyleSheet/processTransform.js
@@ -152,7 +152,7 @@ const _getKeyAndValueFromCSSTransform: (
       };
 
     default:
-      return {key, value: !isNaN(args) ? Number(args) : args};
+      return {key, value: !isNaN(Number(args)) ? Number(args) : args};
   }
 };
 
diff --git a/packages/rn-tester/js/examples/SectionList/SectionList-scrollable.js b/packages/rn-tester/js/examples/SectionList/SectionList-scrollable.js
index 203e6fb5811a..7f1bffdabe43 100644
--- a/packages/rn-tester/js/examples/SectionList/SectionList-scrollable.js
+++ b/packages/rn-tester/js/examples/SectionList/SectionList-scrollable.js
@@ -205,7 +205,7 @@ export component SectionList_scrollable() {
   }
 
   const setItemPress = (item: Item) => {
-    if (isNaN(item.key)) {
+    if (isNaN(Number(item.key))) {
       return;
     }
     const index = Number(item.key);
diff --git a/packages/rn-tester/js/examples/XHR/XHRExampleDownload.js b/packages/rn-tester/js/examples/XHR/XHRExampleDownload.js
index bf8c6b5e717c..72f6eb283a93 100644
--- a/packages/rn-tester/js/examples/XHR/XHRExampleDownload.js
+++ b/packages/rn-tester/js/examples/XHR/XHRExampleDownload.js
@@ -60,7 +60,7 @@ class XHRExampleDownload extends React.Component<{...}, any> {
     const onreadystatechange = () => {
       if (xhr.readyState === xhr.HEADERS_RECEIVED) {
         const contentLength = parseInt(
-          xhr.getResponseHeader('Content-Length'),
+          String(xhr.getResponseHeader('Content-Length')),
           10,
         );
         this.setState({