Expo FileSystem

import { File, Paths } from 'expo-file-system';

try {
  const file = new File(Paths.cache, 'example.txt');
  file.create(); // can throw an error if the file already exists or no permission to create it
  file.write('Hello, world!');
  console.log(file.textSync()); // Hello, world!
} catch (error) {
  console.error(error);
}

import { File } from 'expo-file-system';
import * as DocumentPicker from 'expo-document-picker';

try {
  const result = await DocumentPicker.getDocumentAsync({ copyToCacheDirectory: true });
  if (!result.canceled) {
    const { uri } = result.assets[0];
    const file = new File(uri);
    console.log(file.textSync());
  }
} catch (error) {
  console.error(error);
}

import { File } from 'expo-file-system';

try {
  const file = new File.pickFileAsync();
  console.log(file.textSync());
} catch (error) {
  console.error(error);
}

import { Directory, File, Paths } from 'expo-file-system';

const url = 'https://pdfobject.com/pdf/sample.pdf';
const destination = new Directory(Paths.cache, 'pdfs');
try {
  destination.create();
  const output = await File.downloadFileAsync(url, destination);
  console.log(output.exists); // true
  console.log(output.uri); // path to the downloaded file, e.g., '${cacheDirectory}/pdfs/sample.pdf'
} catch (error) {
  console.error(error);
}

import { fetch } from 'expo/fetch';
import { File, Paths } from 'expo-file-system';

const url = 'https://pdfobject.com/pdf/sample.pdf';
const response = await fetch(url);
const src = new File(Paths.cache, 'file.pdf');
src.write(await response.bytes());

import { fetch } from 'expo/fetch';
import { File, Paths } from 'expo-file-system';

const file = new File(Paths.cache, 'file.txt');
file.write('Hello, world!');

const response = await fetch('https://example.com', {
  method: 'POST',
  body: file,
});

import { fetch } from 'expo/fetch';
import { File, Paths } from 'expo-file-system';

const file = new File(Paths.cache, 'file.txt');
file.write('Hello, world!');
const formData = new FormData();
formData.append('data', file);
const response = await fetch('https://example.com', {
  method: 'POST',
  body: formData,
});

import { Directory, File, Paths } from 'expo-file-system';
try {
  const file = new File(Paths.document, 'example.txt');
  file.create();
  console.log(file.uri); // '${documentDirectory}/example.txt'
  const copiedFile = new File(Paths.cache, 'example-copy.txt');
  file.copy(copiedFile);
  console.log(copiedFile.uri); // '${cacheDirectory}/example-copy.txt'
  file.move(Paths.cache);
  console.log(file.uri); // '${cacheDirectory}/example.txt'
  file.move(new Directory(Paths.cache, 'newFolder'));
  console.log(file.uri); // '${cacheDirectory}/newFolder/example.txt'
} catch (error) {
  console.error(error);
}

import * as FileSystem from 'expo-file-system/legacy';
import { File, Paths } from 'expo-file-system';

try {
  const file = new File(Paths.cache, 'example.txt');
  const content = await FileSystem.readAsStringAsync(file.uri);
  console.log(content);
} catch (error) {
  console.error(error);
}

import { Directory, Paths } from 'expo-file-system';

function printDirectory(directory: Directory, indent: number = 0) {
  console.log(`${' '.repeat(indent)} + ${directory.name}`);
  const contents = directory.list();
  for (const item of contents) {
    if (item instanceof Directory) {
      printDirectory(item, indent + 2);
    } else {
      console.log(`${' '.repeat(indent + 2)} - ${item.name} (${item.size} bytes)`);
    }
  }
}

try {
  printDirectory(new Directory(Paths.cache));
} catch (error) {
  console.error(error);
}