docs.sheetjs.com/docz/docs/03-demos/02-mobile/01-reactnative.md

---
title: React Native
pagination_prev: demos/frontend/index
pagination_next: demos/desktop/index
sidebar_position: 1
sidebar_custom_props:
  summary: React + Native Rendering
---

import Tabs from '@theme/Tabs';
import TabItem from '@theme/TabItem';

The [NodeJS Module](/docs/getting-started/installation/nodejs) can be imported
from the main `App.js` entrypoint or any script in the project.

The "Complete 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>


## Native Libraries

:::warning

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).  "Copy" indicates whether an explicit copy
is needed (file picker copies to cache directory and file plugin reads cache).

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

### RN File Picker

The following libraries have been tested:

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

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

When a copy is not needed:

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

const f = await pickSingle({allowMultiSelection: false, mode: "open" });
const path = f.uri; // this path can be read by RN file plugins
```

When a copy is needed:

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

const f = await pickSingle({allowMultiSelection: false, 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;
```

</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`

On the day that this demo was tested (2022 August 14), both `rn-fetch-blob` and
`react-native-blob-util` 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 show)</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

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 show)</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 show)</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

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

This demo was tested on an Intel Mac on 2022 August 14 with RN `0.67.2`.

The iOS simulator runs iOS 15.5 on an iPhone 13.

The Android simulator runs Android 12 (S) Platform 31 on a Pixel 5.

:::

:::warning

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.  Details like creating an Android Virtual Device
are not covered here.

:::

This example tries to separate the library-specific functions.

0) **Follow the official React Native CLI Guide!**

Development Environment Guide: <https://reactnative.dev/docs/environment-setup>

Follow the instructions for iOS and for Android.  They will cover installation
and system configuration.  By the end, you should be able to run the sample app
in the Android and the iOS simulators.

1) Create project:

```
npx react-native init SheetJSRN --version="0.67.2"
```

2) Install shared dependencies:

```bash
cd SheetJSRN
curl -LO https://oss.sheetjs.com/assets/img/logo.png
npm i -S https://cdn.sheetjs.com/xlsx-latest/xlsx-latest.tgz
npm i -S react-native-table-component react-native-document-picker
```

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:///mobile/rnios1.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
```

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() {
  /* rn-fetch-blob / react-native-blob-util need a copy */
  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 RNFetchBlob.fs.readFile(path, 'ascii');
  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
```

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 { Dirs, FileSystem } from 'react-native-file-access';

async function pickAndParse() {
  /* react-native-file-access does not need a copy */
  const f = await pickSingle({allowMultiSelection: false, mode: "open" });
  const res = await FileSystem.readFile(f.uri, "base64");
  return read(res, {type: 'base64'});
}

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
```

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() {
  /* rn-fetch-blob / react-native-blob-util need a copy */
  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 RNFetchBlob.fs.readFile(path, 'ascii');
  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
```

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() {
  /* react-native-fs needs a copy */
  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">

:::caution

At the time of testing, the `npx install-expo-modules` step breaks the Android
project. The demo works as expected on iOS.

:::

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

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

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:///mobile/rnios3.png)

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

![write file iOS](pathname:///mobile/rnios4.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:///mobile/rnand1.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:///mobile/rnand3.png)

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

![write file Android](pathname:///mobile/rnand4.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
```