docs.sheetjs.com/docz/docs/03-demos/17-mobile/01-reactnative.md

---
title: React Native
sidebar_label: React Native
description: Build data-intensive mobile apps with React Native. Seamlessly integrate spreadsheets into your app using SheetJS. Securely process and generate Excel files in the field.
pagination_prev: demos/static/index
pagination_next: demos/desktop/index
sidebar_position: 1
sidebar_custom_props:
  summary: React + Native Rendering
---

# Sheets on the Go with React Native

import current from '/version.js';
import Tabs from '@theme/Tabs';
import TabItem from '@theme/TabItem';
import CodeBlock from '@theme/CodeBlock';

[React Native](https://reactnative.dev/) is a mobile app framework. It builds
iOS and Android apps that use JavaScript for describing layouts and events.

[SheetJS](https://sheetjs.com) is a JavaScript library for reading and writing
data from spreadsheets.

This demo uses React Native and SheetJS to process and generate spreadsheets.
We'll explore how to load SheetJS in a React Native app in a few ways:

- ["Fetching Remote Data"](#fetching-remote-data) uses the built-in `fetch` to
download and parse remote workbook files.
- ["Local Files"](#local-files) uses native libraries to read and write files on
the device.

The "Local Files" example creates an app that looks like the screenshots below:

<table><thead><tr>
  <th><a href="#demo">iOS</a></th>
  <th><a href="#demo">Android</a></th>
</tr></thead><tbody><tr><td>

![iOS screenshot](pathname:///mobile/rnios3.png)

</td><td>

![Android screenshot](pathname:///mobile/rnand3.png)

</td></tr></tbody></table>

:::caution pass

**Before testing this demo, follow the official React Native CLI Guide!**[^1]

Follow the instructions for iOS (requires macOS) and for Android. They will
cover installation and system configuration. You should be able to build and run
a sample app in the Android and the iOS (if applicable) simulators.

:::

## Integration Details

The [SheetJS NodeJS Module](/docs/getting-started/installation/nodejs) can be
imported from any component or script in the app.

### Internal State

For simplicity, this demo uses an "Array of Arrays"[^2] as the internal state.

<table><thead><tr><th>Spreadsheet</th><th>Array of Arrays</th></tr></thead><tbody><tr><td>

![`pres.xlsx` data](pathname:///pres.png)

</td><td>

```js
[
  ["Name", "Index"],
  ["Bill Clinton", 42],
  ["GeorgeW Bush", 43],
  ["Barack Obama", 44],
  ["Donald Trump", 45],
  ["Joseph Biden", 46]
]
```

</td></tr></tbody></table>

Each array within the structure corresponds to one row.

This demo also keeps track of the column widths as a single array of numbers.
The widths are used by the display component.

_Complete State_

The complete state is initialized with the following snippet:

```js
const [data, setData] = useState([
  "SheetJS".split(""),
  [5,4,3,3,7,9,5],
  [8,6,7,5,3,0,9]
]);
const [widths, setWidths] = useState(Array.from({length:7}, () => 20));
```


#### Updating State

Starting from a SheetJS worksheet object, `sheet_to_json`[^3] with the `header`
option can generate an array of arrays:

```js
/* assuming `wb` is a SheetJS workbook */
function update_state(wb) {
  /* convert first worksheet to AOA */
  const wsname = wb.SheetNames[0];
  const ws = wb.Sheets[wsname];
  const data = utils.sheet_to_json(ws, {header:1});

  /* update state */
  setData(data);

  /* update column widths */
  setWidths(make_width(data));
}
```

_Calculating Column Widths_

Column widths can be calculated by walking each column and calculating the max
data width. Using the array of arrays:

```js
/* this function takes an array of arrays and generates widths */
function make_width(aoa) {
  /* walk each row */
  aoa.forEach((r) => {
    /* walk each column */
    r.forEach((c, C) => {
      /* update column width based on the length of the cell contents */
      res[C] = Math.max(res[C]||60, String(c).length * 10);
    });
  });
  /* use a default value for columns with no data */
  for(let C = 0; C < res.length; ++C) if(!res[C]) res[C] = 60;
  return res;
}
```

#### Exporting State

`aoa_to_sheet`[^4] builds a SheetJS worksheet object from the array of arrays:

```js
/* generate a SheetJS workbook from the state */
function export_state() {
  /* convert AOA back to worksheet */
  const ws = utils.aoa_to_sheet(data);

  /* build new workbook */
  const wb = utils.book_new();
  utils.book_append_sheet(wb, ws, "SheetJS");

  return wb;
}
```

### Displaying Data

The demos uses `react-native-table-component` to display the first worksheet.

The demos use components similar to the example below:

```jsx
import { ScrollView } from 'react-native';
import { Table, Row, Rows, TableWrapper } from 'react-native-table-component';

(
  {/* Horizontal scroll */}
  <ScrollView horizontal={true} >
    {/* Table container */}
    <Table>
      {/* Frozen Header Row */}
      <TableWrapper>
        {/* First row */}
        <Row data={data[0]} widthArr={widths}/>
      </TableWrapper>
      {/* Scrollable Data Rows */}
      <ScrollView>
        <TableWrapper>
          {/* Remaining Rows */}
          <Rows data={data.slice(1)} widthArr={widths}/>
        </TableWrapper>
      </ScrollView>
    </Table>
  </ScrollView>
)
```

`data.slice(1)` in the `Rows` component returns data starting from the second
row. This neatly skips the first header row.

## Fetching Remote Data

React Native versions starting from `0.72.0`[^5] support binary data in `fetch`.

This snippet downloads and parses <https://sheetjs.com/pres.xlsx>:

```js
/* fetch data into an ArrayBuffer */
const ab = await (await fetch("https://sheetjs.com/pres.xlsx")).arrayBuffer();
/* parse data */
const wb = XLSX.read(ab);
```

### Fetch Demo

:::note Tested Deployments

This demo was tested in the following environments:

**Simulators**

| OS         | Device            | RN       | Dev Platform | Date       |
|:-----------|:------------------|:---------|:-------------|:-----------|
| Android 34 | Pixel 3a          | `0.73.6` | `darwin-x64` | 2024-03-13 |
| iOS 17.4   | iPhone 15 Pro Max | `0.73.6` | `darwin-x64` | 2024-03-13 |
| Android 34 | Pixel 3a          | `0.73.5` | `win10-x64`  | 2024-03-05 |

**Real Devices**

| OS         | Device            | RN       | Date       |
|:-----------|:------------------|:---------|:-----------|
| iOS 15.1   | iPhone 12 Pro Max | `0.73.6` | 2024-03-13 |
| Android 29 | NVIDIA Shield     | `0.73.6` | 2024-03-13 |

:::

1) Create project:

```bash
npx -y react-native@0.73.6 init SheetJSRNFetch --version="0.73.6"
```

2) Install shared dependencies:

<CodeBlock language="bash">{`\
cd SheetJSRNFetch
curl -LO https://docs.sheetjs.com/logo.png
npm i -S https://cdn.sheetjs.com/xlsx-${current}/xlsx-${current}.tgz
npm i -S react-native-table-component@1.2.0 @types/react-native-table-component`}
</CodeBlock>

3) Download [`App.tsx`](pathname:///reactnative/App.tsx) and replace:

```bash
curl -LO https://docs.sheetjs.com/reactnative/App.tsx
```

**Android Testing**

4) Install or switch to Java 17[^6]

:::note pass

When the demo was last tested on macOS, `java -version` displayed the following:

```
openjdk version "17.0.10" 2024-01-16
OpenJDK Runtime Environment Temurin-17.0.10+7 (build 17.0.10+7)
OpenJDK 64-Bit Server VM Temurin-17.0.10+7 (build 17.0.10+7, mixed mode)
```

:::

5) Start the Android emulator:

```bash
npx react-native run-android
```

:::caution pass

If the initial launch fails with an error referencing the emulator, manually
start the emulator from Android Studio and try again.

Gradle errors typically stem from a Java version mismatch:

```
> Failed to apply plugin 'com.android.internal.application'.
   > Android Gradle plugin requires Java 17 to run. You are currently using Java 11.
```

This error can be resolved by installing and switching to the requested version.

:::

6) When opened, the app should look like the "Before" screenshot below. After
tapping "Import data from a spreadsheet", verify that the app shows new data:

<table><thead><tr>
  <th>Before</th>
  <th>After</th>
</tr></thead><tbody><tr><td>

![before screenshot](pathname:///reactnative/andfetch1.png)

</td><td>

![after screenshot](pathname:///reactnative/andfetch2.png)

</td></tr></tbody></table>

**iOS Testing**

:::warning pass

**iOS testing can only be performed on Apple hardware running macOS!**

Xcode and iOS simulators are not available on Windows or Linux.

:::

7) Refresh iOS project by running `pod install` from the `ios` subfolder:

```bash
cd ios; pod install; cd ..
```

8) Start the iOS emulator:

```bash
npx react-native run-ios
```

9) When opened, the app should look like the "Before" screenshot below.  After
tapping "Import data from a spreadsheet", verify that the app shows new data:

<table><thead><tr>
  <th>Before</th>
  <th>After</th>
</tr></thead><tbody><tr><td>

![before screenshot](pathname:///reactnative/iosfetch1.png)

</td><td>

![after screenshot](pathname:///reactnative/iosfetch2.png)

</td></tr></tbody></table>

**Android Device Testing**

10) Connect an Android device using a USB cable.

If the device asks to allow USB debugging, tap "Allow".

11) Close any Android / iOS emulators.

12) Build APK and run on device:

```bash
npx react-native run-android
```

**iOS Device Testing**

13) Close any Android / iOS emulators.

14) Enable developer code signing certificates[^7].

<details open><summary><b>Enabling Code Signing</b> (click to show)</summary>

These instructions were verified against Xcode 15.3.

A) Open the included iOS workspace in Xcode:

```bash
open ios/SheetJSRNFetch.xcworkspace
```

B) Select "SheetJSRNFetch" in the Project Navigator:

![Select the project](pathname:///reactnative/xcode-select-project.png)

C) Select "Signing & Capabilities" in the main view.

D) Select "All" in the lower bar and ensure a Team is selected in the dropdown:

![Xcode Signing and Capabilities](pathname:///reactnative/xcode-sign-cap.png)

</details>

15) Install `ios-deploy` through Homebrew:

```bash
brew install ios-deploy
```

16) Run on device:

```bash
npx react-native run-ios
```

:::caution pass

In some tests, the app failed to run on the device due to "Untrusted Developer":

```
Your device management settings do not allow apps from developer ... on this iPhone. You can allow using these apps in Settings.
```

These instructions were verified against iOS 15.1.

A) Open the Settings app and select "General" > "VPN & Device Management".

![iOS Management](pathname:///reactnative/ios-mgmt.png)

B) Select the Apple Development certificate under "Developer App".

![iOS Certificate Info](pathname:///reactnative/ios-cert.png)

In the new screen, the name "SheetJSRNFetch" will be displayed in the Apps list.

C) Tap "Trust ..." and tap "Trust" in the popup.

![iOS Trust Popup](pathname:///reactnative/ios-trust.png)

D) Close the Settings app on the device.

E) Close the Metro window on the computer.

F) Run `npx react-native run-ios` again.

:::

:::note pass

In some tests, the build failed with the following error:

```
PhaseScriptExecution failed with a nonzero exit code
```

This was due to an error in the `react-native` package. The script
`node_modules/react-native/scripts/react-native-xcode.sh` must be edited.

Near the top of the script, there will be a `set` statement:

```bash title="node_modules/react-native/scripts/react-native-xcode.sh"
# Print commands before executing them (useful for troubleshooting)
# highlight-next-line
set -x -e
DEST=$CONFIGURATION_BUILD_DIR/$UNLOCALIZED_RESOURCES_FOLDER_PATH
```

The `-e` argument must be removed:

```bash title="node_modules/react-native/scripts/react-native-xcode.sh (edit line)"
# Print commands before executing them (useful for troubleshooting)
# highlight-next-line
set -x
DEST=$CONFIGURATION_BUILD_DIR/$UNLOCALIZED_RESOURCES_FOLDER_PATH
```

:::

:::caution pass

In some test runs, the error mentioned a development team:

```
error: Signing for "SheetJSRNFetch" requires a development team. Select a development team in the Signing & Capabilities editor. (in target 'SheetJSRNFetch' from project 'SheetJSRNFetch')
```

Code signing must be enabled in the project!

:::

:::info pass

By default, React Native generates applications that exclusively target iPhone.
On a physical iPad, a pixellated iPhone app will be run.

The "targeted device families" setting must be changed to support iPad:

A) Open the Xcode workspace:

```bash
open ./ios/SheetJSRNFetch.xcworkspace
```

B) Select the project in the left sidebar:

![Select the project](pathname:///reactnative/xcode-select-project.png)

C) Select the "SheetJSRNFetch" target in the sidebar.

![Settings](pathname:///reactnative/xcode-targets.png)

D) Select the "Build Settings" tab in the main area.

E) In the search bar below "Build Settings", type "tar"

F) In the "Targeted Device Families" row, change the value to "iPhone, iPad".

:::

## Local Files

:::warning pass

React Native does not provide a native file picker or a method for reading and
writing data from documents on the devices. A third-party library must be used.

Since React Native internals change between releases, libraries may only work
with specific versions of React Native.  Project documentation should be
consulted before picking a library.

:::

The following table lists tested file plugins.  "OS" lists tested platforms
("A" for Android and "I" for iOS).

| File system Plugin         | File Picker Plugin             |  OS  |
|:---------------------------|:-------------------------------|:----:|
| `react-native-file-access` | `react-native-document-picker` | `AI` |
| `react-native-blob-util`   | `react-native-document-picker` | `AI` |
| `rn-fetch-blob`            | `react-native-document-picker` | `AI` |
| `react-native-fs`          | `react-native-document-picker` | `AI` |
| `expo-file-system`         | `expo-document-picker`         | ` I` |

### RN File Picker

The "File Picker" library handles two platform-specific steps:

1) Show a view that allows users to select a file from their device

2) Copy the selected file to a location that can be read by the application

The following libraries have been tested:

#### `react-native-document-picker`

<details open><summary><b>Selecting a file</b> (click to hide)</summary>

The setting `copyTo: "cachesDirectory"` must be set:

```js
import { pickSingle } from 'react-native-document-picker';

const f = await pickSingle({
  allowMultiSelection: false,
  // highlight-next-line
  copyTo: "cachesDirectory",
  mode: "open"
});
const path = f.fileCopyUri; // this path can be read by RN file plugins
```

</details>

#### `expo-document-picker`

<details><summary><b>Selecting a file</b> (click to show)</summary>

When using `DocumentPicker.getDocumentAsync`, enable `copyToCacheDirectory`:

```js
import * as DocumentPicker from 'expo-document-picker';

const result = await DocumentPicker.getDocumentAsync({
  // highlight-next-line
  copyToCacheDirectory: true,
  type: ['application/vnd.ms-excel', 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet']
});
const path = result.uri; // this path can be read by RN file plugins
```

</details>


### RN File Plugins

The following libraries have been tested:

#### `react-native-blob-util` and `rn-fetch-blob`

:::note Historical Context

The `react-native-fetch-blob` project was archived in 2019. At the time, there
were a number of project forks.  The maintainers blessed the `rn-fetch-blob`
fork as the spiritual successor.

`react-native-blob-util` is an active fork of `rn-fetch-blob`

When this demo was last tested, `rn-fetch-blob` and `react-native-blob-util`
both worked with the tested iOS and Android SDK versions. The APIs are identical
for the purposes of working with files.

:::

The `ascii` type returns an array of numbers corresponding to the raw bytes.
A `Uint8Array` from the data is compatible with the `buffer` type.

<details open><summary><b>Reading and Writing snippets</b> (click to hide)</summary>

The snippets use `rn-fetch-blob`.  To use `react-native-blob-util`, change the
`import` statements to load the module.

_Reading Data_

```js
import * as XLSX from "xlsx";
import RNFetchBlob from 'rn-fetch-blob'; // or react-native-blob-util
const { readFile } = RNFetchBlob.fs;

const res = await readFile(path, 'ascii');
const wb = XLSX.read(new Uint8Array(res), {type:'buffer'});
```

:::caution pass

On iOS, the URI from `react-native-document-picker` must be massaged:

```js
import { pickSingle } from 'react-native-document-picker';
import RNFetchBlob from 'rn-fetch-blob'; // or react-native-blob-util
const { readFile, dirs: { DocumentDir } } = RNFetchBlob.fs;

const f = await pickSingle({
// highlight-start
  // Instruct the document picker to copy file to Documents directory
  copyTo: "documentDirectory",
// highlight-end
  allowMultiSelection: false, mode: "open" });
// highlight-start
// `f.uri` is the original path and `f.fileCopyUri` is the path to the copy
let path = f.fileCopyUri;
// iOS workaround
if (Platform.OS === 'ios') path = path.replace(/^.*\/Documents\//, DDP + "/");
// highlight-end

const res = await readFile(path, 'ascii');
```

:::

_Writing Data_

```js
import * as XLSX from "xlsx";
import RNFetchBlob from 'rn-fetch-blob'; // or react-native-blob-util
const { writeFile, readFile, dirs:{ DocumentDir } } = RNFetchBlob.fs;

const wbout = XLSX.write(wb, {type:'buffer', bookType:"xlsx"});
const file = DocumentDir + "/sheetjsw.xlsx";
const res = await writeFile(file, Array.from(wbout), 'ascii');
```


</details>

#### `react-native-file-access`

The `base64` encoding returns strings compatible with the `base64` type:

<details open><summary><b>Reading and Writing snippets</b> (click to hide)</summary>

_Reading Data_

```js
import * as XLSX from "xlsx";
import { FileSystem } from "react-native-file-access";

const b64 = await FileSystem.readFile(path, "base64");
/* b64 is a Base64 string */
const workbook = XLSX.read(b64, {type: "base64"});
```

_Writing Data_

```js
import * as XLSX from "xlsx";
import { Dirs, FileSystem } from "react-native-file-access";
const DDP = Dirs.DocumentDir + "/";

const b64 = XLSX.write(workbook, {type:'base64', bookType:"xlsx"});
/* b64 is a Base64 string */
await FileSystem.writeFile(DDP + "sheetjs.xlsx", b64, "base64");
```

</details>

#### `react-native-fs`

The `ascii` encoding returns binary strings compatible with the `binary` type:

<details open><summary><b>Reading and Writing snippets</b> (click to hide)</summary>

_Reading Data_

```js
import * as XLSX from "xlsx";
import { readFile } from "react-native-fs";

const bstr = await readFile(path, "ascii");
/* bstr is a binary string */
const workbook = XLSX.read(bstr, {type: "binary"});
```

_Writing Data_

```js
import * as XLSX from "xlsx";
import { writeFile, DocumentDirectoryPath } from "react-native-fs";

const bstr = XLSX.write(workbook, {type:'binary', bookType:"xlsx"});
/* bstr is a binary string */
await writeFile(DocumentDirectoryPath + "/sheetjs.xlsx", bstr, "ascii");
```

</details>

#### `expo-file-system`

:::caution pass

Some Expo APIs return URI that cannot be read with `expo-file-system`. This
will manifest as an error:

> Unsupported scheme for location '...'

The [`expo-document-picker`](#expo-document-picker) snippet makes a local copy.

:::

The `EncodingType.Base64` encoding is compatible with `base64` type.

<details><summary><b>Reading and Writing snippets</b> (click to show)</summary>

_Reading Data_

Calling `FileSystem.readAsStringAsync` with `FileSystem.EncodingType.Base64`
encoding returns a promise resolving to a string compatible with `base64` type:

```js
import * as XLSX from "xlsx";
import * as FileSystem from 'expo-file-system';

const b64 = await FileSystem.readAsStringAsync(uri, { encoding: FileSystem.EncodingType.Base64 });
const workbook = XLSX.read(b64, { type: "base64" });
```

_Writing Data_

The `FileSystem.EncodingType.Base64` encoding accepts Base64 strings:

```js
import * as XLSX from "xlsx";
import * as FileSystem from 'expo-file-system';

const b64 = XLSX.write(workbook, {type:'base64', bookType:"xlsx"});
/* b64 is a Base64 string */
await FileSystem.writeAsStringAsync(FileSystem.documentDirectory + "sheetjs.xlsx", b64, { encoding: FileSystem.EncodingType.Base64 });
```

</details>

### Demo

:::note Tested Deployments

Each Android demo was last tested on 2023 September 03 with RN `0.72.6`. The
simulator used Android 13 ("Tiramisu") API 33 on a Pixel 3.

Each iOS demo was last tested on 2023 September 03 with RN `0.72.6`. The
simulator used iOS 17.0 on an iPhone 15 Pro Max.

:::

:::warning pass

There are many moving parts and pitfalls with React Native apps. It is strongly
recommended to follow the official React Native tutorials for iOS and Android
before approaching this demo.[^8] Details including Android Virtual Device
configuration are not covered here.

:::

This example tries to separate the library-specific functions.

1) Create project:

```bash
npx react-native init SheetJSRN --version="0.72.6"
```

2) Install shared dependencies:

<CodeBlock language="bash">{`\
cd SheetJSRN
curl -LO https://docs.sheetjs.com/logo.png
npm i -S https://cdn.sheetjs.com/xlsx-${current}/xlsx-${current}.tgz
npm i -S react-native-table-component@1.2.0 react-native-document-picker@8.2.0`}
</CodeBlock>

Refresh iOS project by running `pod install` from the `ios` subfolder:

```bash
cd ios
pod install
cd ..
```

3) Download [`index.js`](pathname:///mobile/index.js) and replace:

```bash
curl -LO https://docs.sheetjs.com/mobile/index.js
```

Start the iOS emulator:

```bash
npx react-native run-ios
```

You should see the skeleton app:

![React Native iOS App](pathname:///reactnative/ios1.png)

4) Pick a filesystem library for integration:


<Tabs>
  <TabItem value="RNBU" label="RNBU">

Install `react-native-blob-util` dependency:

```bash
npm i -S react-native-blob-util@0.19.2
```

Add the highlighted lines to `index.js`:

```js title="index.js"
import { Table, Row, Rows, TableWrapper } from 'react-native-table-component';

// highlight-start
import { read, write } from 'xlsx';
import { pickSingle } from 'react-native-document-picker';
import { Platform } from 'react-native';
import RNFetchBlob from 'react-native-blob-util';

async function pickAndParse() {
  const f = await pickSingle({allowMultiSelection: false, copyTo: "documentDirectory", mode: "open" });
  let path = f.fileCopyUri;
  if (Platform.OS === 'ios') path = path.replace(/^.*\/Documents\//, RNFetchBlob.fs.dirs.DocumentDir + "/");
  const res = await (await fetch(path)).arrayBuffer(); // RN >= 0.72
  // const res = await RNFetchBlob.fs.readFile(path, 'ascii'); // RN < 0.72
  return read(new Uint8Array(res), {type: 'buffer'});
}

async function writeWorkbook(wb) {
  const wbout = write(wb, {type:'buffer', bookType:"xlsx"});
  const file = RNFetchBlob.fs.dirs.DocumentDir + "/sheetjsw.xlsx";
  await RNFetchBlob.fs.writeFile(file, Array.from(wbout), 'ascii');
  return file;
}
// highlight-end

const make_width = ws => {
```

  </TabItem>
  <TabItem value="RNFA" label="RNFA">

Install `react-native-file-access` dependency:

```bash
npm i -S react-native-file-access@3.0.4
```

Add the highlighted lines to `index.js`:

```js title="index.js"
import { Table, Row, Rows, TableWrapper } from 'react-native-table-component';

// highlight-start
import { read, write } from 'xlsx';
import { pickSingle } from 'react-native-document-picker';
import { Platform } from 'react-native';
import { Dirs, FileSystem } from 'react-native-file-access';

async function pickAndParse() {
  const f = await pickSingle({allowMultiSelection: false, copyTo: "documentDirectory", mode: "open" });
  let path = f.fileCopyUri;
  const res = await (await fetch(path)).arrayBuffer();
  return read(new Uint8Array(res), {type: 'buffer'});
}

async function writeWorkbook(wb) {
  const wbout = write(wb, {type:'base64', bookType:"xlsx"});
  const file = Dirs.DocumentDir + "/sheetjsw.xlsx";
  await FileSystem.writeFile(file, wbout, "base64");
  return file;
}
// highlight-end

const make_width = ws => {
```

  </TabItem>
  <TabItem value="RNFB" label="RNFB">

Install `rn-fetch-blob` dependency:

```bash
npm i -S rn-fetch-blob@0.12.0
```

Add the highlighted lines to `index.js`:

```js title="index.js"
import { Table, Row, Rows, TableWrapper } from 'react-native-table-component';

// highlight-start
import { read, write } from 'xlsx';
import { pickSingle } from 'react-native-document-picker';
import { Platform } from 'react-native';
import RNFetchBlob from 'rn-fetch-blob';

async function pickAndParse() {
  const f = await pickSingle({allowMultiSelection: false, copyTo: "documentDirectory", mode: "open" });
  let path = f.fileCopyUri;
  if (Platform.OS === 'ios') path = path.replace(/^.*\/Documents\//, RNFetchBlob.fs.dirs.DocumentDir + "/");
  const res = await (await fetch(path)).arrayBuffer(); // RN >= 0.72
  // const res = await RNFetchBlob.fs.readFile(path, 'ascii'); // RN < 0.72
  return read(new Uint8Array(res), {type: 'buffer'});
}

async function writeWorkbook(wb) {
  const wbout = write(wb, {type:'buffer', bookType:"xlsx"});
  const file = RNFetchBlob.fs.dirs.DocumentDir + "/sheetjsw.xlsx";
  await RNFetchBlob.fs.writeFile(file, Array.from(wbout), 'ascii');
  return file;
}
// highlight-end

const make_width = ws => {
```

  </TabItem>
  <TabItem value="RNFS" label="RNFS">

Install `react-native-fs` dependency:

```bash
npm i -S react-native-fs@2.20.0
```

Add the highlighted lines to `index.js`:

```js title="index.js"
import { Table, Row, Rows, TableWrapper } from 'react-native-table-component';

// highlight-start
import { read, write } from 'xlsx';
import { pickSingle } from 'react-native-document-picker';
import { writeFile, readFile, DocumentDirectoryPath } from 'react-native-fs';

async function pickAndParse() {
  const f = await pickSingle({allowMultiSelection: false, copyTo: "cachesDirectory", mode: "open" });
  const bstr = await readFile(f.fileCopyUri, 'ascii');
  return read(bstr, {type:'binary'});
}

async function writeWorkbook(wb) {
  const wbout = write(wb, {type:'binary', bookType:"xlsx"});
  const file = DocumentDirectoryPath + "/sheetjsw.xlsx";
  await writeFile(file, wbout, 'ascii');
  return file;
}
// highlight-end

const make_width = ws => {
```

  </TabItem>
  <TabItem value="EXPO" label="EXPO">

:::warning pass

At the time of testing, Expo Modules were incompatible with Android projects.

:::

Install `expo-file-system` and `expo-document-picker` dependencies:

```bash
npx install-expo-modules
npm i -S expo-file-system expo-document-picker
```

:::note pass

In the most recent test, the installation asked a few questions.

If prompted to change iOS deployment target, choose Yes.

If prompted to install Expo CLI integration, choose No.

:::

Add the highlighted lines to `index.js`:

```js title="index.js"
import { Table, Row, Rows, TableWrapper } from 'react-native-table-component';

// highlight-start
import { read, write } from 'xlsx';
import { getDocumentAsync } from 'expo-document-picker';
import { documentDirectory, readAsStringAsync, writeAsStringAsync } from 'expo-file-system';

async function pickAndParse() {
  const result = await getDocumentAsync({copyToCacheDirectory: true});
  const path = result.uri;
  const res = await readAsStringAsync(path, { encoding: "base64" });
  return read(res, {type: 'base64'});
}

async function writeWorkbook(wb) {
  const wbout = write(wb, {type:'base64', bookType:"xlsx"});
  const file = documentDirectory + "sheetjsw.xlsx";
  await writeAsStringAsync(file, wbout, { encoding: "base64" });
  return file;
}
// highlight-end

const make_width = ws => {
```

  </TabItem>
</Tabs>


5) Refresh the app:

```bash
cd ios
pod install
cd ..
```

Once refreshed, the development process must be restarted:

```bash
npx react-native run-ios
```

**iOS Testing**

The app can be tested with the following sequence in the simulator:

- Download <https://sheetjs.com/pres.numbers>
- In the simulator, click the Home icon to return to the home screen
- Click on the "Files" icon
- Click and drag `pres.numbers` from a Finder window into the simulator.

![save file iOS](pathname:///mobile/quasar7a.png)

- Make sure "On My iPhone" is highlighted and select "Save"
- Click the Home icon again then select the `SheetJSRN` app
- Click "Import data" and select `pres`:

![pick file iOS](pathname:///mobile/rnios2.png)

Once selected, the screen should refresh with new contents:

![read file iOS](pathname:///reactnative/ios3.png)

- Click "Export data".  You will see a popup with a location:

![write file iOS](pathname:///reactnative/ios4.png)

- Find the file and verify the contents are correct:

```bash
find ~/Library/Developer/CoreSimulator -name sheetjsw.xlsx |
  while read x; do echo "$x"; npx xlsx-cli "$x"; done
```

Once testing is complete, stop the simulator and the development process.

**Android Testing**

There are no Android-specific steps.  Emulator can be started with:

```bash
npx react-native run-android
```

![React Native Android App](pathname:///reactnative/and1.png)

The app can be tested with the following sequence in the simulator:

- Download <https://sheetjs.com/pres.numbers>
- Click and drag `pres.numbers` from a Finder window into the simulator.
- Click "Import data" and select `pres.numbers`:

![pick file Android](pathname:///mobile/rnand2.png)

Once selected, the screen should refresh with new contents:

![read file Android](pathname:///reactnative/and3.png)

- Click "Export data".  You will see a popup with a location:

![write file Android](pathname:///reactnative/and4.png)

- Pull the file from the simulator and verify the contents:

```bash
adb exec-out run-as com.sheetjsrn cat files/sheetjsw.xlsx > /tmp/sheetjsw.xlsx
npx xlsx-cli /tmp/sheetjsw.xlsx
```

[^1]: Follow the ["React Native CLI Quickstart"](https://reactnative.dev/docs/environment-setup) and select the appropriate "Development OS".
[^2]: See ["Array of Arrays" in the API reference](/docs/api/utilities/array#array-of-arrays)
[^3]: See ["Array Output" in "Utility Functions"](/docs/api/utilities/array#array-output)
[^4]: See ["Array of Arrays Input" in "Utility Functions"](/docs/api/utilities/array#array-of-arrays-input)
[^5]: React-Native commit [`5b597b5`](https://github.com/facebook/react-native/commit/5b597b5ff94953accc635ed3090186baeecb3873) added the final piece required for `fetch` support. It landed in version `0.72.0-rc.1` and is available in official releases starting from `0.72.0`.
[^6]: When the demo was last tested, the Temurin distribution of Java 17 was installed through the macOS Brew package manager by running `brew install temurin17`. [Direct downloads are available at `adoptium.net`](https://adoptium.net/temurin/releases/?version=17)
[^7]: See ["Running On Device"](https://reactnative.dev/docs/running-on-device) in the React Native documentation
[^8]: Follow the ["React Native CLI Quickstart"](https://reactnative.dev/docs/environment-setup) for Android (and iOS, if applicable)