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New: Sourcemap Page #3293

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24 changes: 1 addition & 23 deletions docs/profile-hermes.md
Original file line number Diff line number Diff line change
Expand Up @@ -42,32 +42,10 @@ npx react-native profile-hermes [destinationDir]

### Enabling source map

A source map is used to enhance the profile and associate trace events with the application code. You can automatically generate a source map when converting the Hermes tracing profile to a Chrome tracing profile by enabling `bundleInDebug` if the app is running in development mode. This allows React Native to build the bundle during its running process. Here's how:

1. In your app's `android/app/build.gradle` file, add:

```groovy
project.ext.react = [
bundleInDebug: true,
]
```

:::info
Be sure to clean the build whenever you make any changes to `build.gradle`
You may read about source maps on the [source maps](sourcemaps.md) page.
:::

2. Clean the build by running:

```sh
cd android && ./gradlew clean
```

3. Run your app:

```sh
npx react-native run-android
```

### Common errors

#### `adb: no devices/emulators found` or `adb: device offline`
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82 changes: 82 additions & 0 deletions docs/sourcemaps.md
Original file line number Diff line number Diff line change
@@ -0,0 +1,82 @@
---
id: sourcemaps
title: Source Maps
---

Source maps allows to map a transformed file back to the original source file. The main purpose of source maps is to aid debugging and help investigating issues from release builds.

Without the source maps, when running into an error in the release build you will see a stacktrace like:

```text
TypeError: Cannot read property 'data' of undefined
at anonymous(app:///index.android.bundle:1:4277021)
at call(native)
at p(app:///index.android.bundle:1:227785)
```

With source maps generated, a stacktrace will include path, file name, and line number of the original source file:

```text
TypeError: Cannot read property 'data' of undefined
at anonymous(src/modules/notifications/Permission.js:15:requestNotificationPermission)
at call(native)
at p(node_modules/regenerator-runtime/runtime.js:64:Generator)
```

This allows to triage release issues given a more accurate stacktrace.

Follow the instructions below to get started with source maps.

## Enable source maps on Android

### Hermes

:::info
Source maps are built in Release mode by default. However, if `hermesFlagsRelease` is set - source maps will have to be enabled.
:::

If so, ensure the following is set in your app's `android/app/build.gradle` file.

```groovy
project.ext.react = [
enableHermes: true,
hermesFlagsRelease: ["-O", "-output-source-map"], // plus whichever flag was required to set this away from default
]
```

If done correctly - you may see the output location of the source map during Metro build output.

```text
Writing bundle output to:, android/app/build/generated/assets/react/release/index.android.bundle
Writing sourcemap output to:, android/app/build/intermediates/sourcemaps/react/release/index.android.bundle.packager.map
```

Development builds do not produce a bundle and thus already have symbols, but if the development build is bundled you may use `hermesFlagsDebug` like above to enable source maps.

## Enable source maps on iOS
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Source maps are disabled by default. To enable them one has to define `SOURCEMAP_FILE` environment variable.

In order to do so, within Xcode head to the build phase - "Bundle React Native code and images".

At the top of the file near the other export's, add an entry for `SOURCEMAP_FILE` to the preferred location and name. Like below:

```
export SOURCEMAP_FILE="$(pwd)/../main.jsbundle.map";

export NODE_BINARY=node
../node_modules/react-native/scripts/react-native-xcode.sh
```

If done correctly - you may see the output location of the source map during Metro build output.

```text
Writing bundle output to:, Build/Intermediates.noindex/ArchiveIntermediates/application/BuildProductsPath/Release-iphoneos/main.jsbundle
Writing sourcemap output to:, Build/Intermediates.noindex/ArchiveIntermediates/application/BuildProductsPath/Release-iphoneos/main.jsbundle.map
```

## Manual Symbolication

:::info
You may read about manual symbolication of a stack trace on the [symbolication](symbolication.md) page.
:::
1 change: 1 addition & 0 deletions website/sidebars.json
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Expand Up @@ -23,6 +23,7 @@
"fast-refresh",
"debugging",
"symbolication",
"sourcemaps",
"testing-overview",
"libraries",
"typescript",
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