expo

docz/docs/06-solutions/01-input.md

@@ -135,6 +135,41 @@ import { readFile } from "react-native-fs";
 const bstr = await readFile(path, "ascii");
 /* bstr is a binary string */
 const workbook = XLSX.read(bstr, {type: "binary"});
+```
+
+- [`expo-file-system`](https://www.npmjs.com/package/expo-file-system)
+
+:::caution
+
+Some Expo APIs return URIs that cannot be read with `expo-file-system`.  This
+will manifest as an error:
+
+> Unsupported scheme for location '...'
+
+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 uri = result.uri;
+```
+
+:::
+
+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" });
 ```
 
   </TabItem>

docz/docs/06-solutions/05-output.md

@@ -258,7 +258,7 @@ The following libraries have been tested:
 
 - [`react-native-file-access`](https://npm.im/react-native-file-access)
 
-The `base64` encoding returns strings compatible with the `base64` type:
+The `base64` encoding accepts Base64 strings compatible with the `binary` type:
 
 ```js
 import * as XLSX from "xlsx";
@@ -282,6 +282,20 @@ const DDP = DocumentDirectoryPath + "/";
 const bstr = XLSX.write(workbook, {type:'binary', bookType:"xlsx"});
 /* bstr is a binary string */
 await writeFile(DDP + "sheetjs.xlsx", bstr, "ascii");
+```
+
+- [`expo-file-system`](https://www.npmjs.com/package/expo-file-system)
+
+The `FileSystem.EncodingType.Base64` encoding accepts Base64 strings:
+
+```js
+import * as XLSX from "xlsx";
+import * as FileSystem from 'expo-file-system';
+const DDP = FileSystem.documentDirectory;
+
+const b64 = XLSX.write(workbook, {type:'base64', bookType:"xlsx"});
+/* b64 is a base64 string */
+await FileSystem.writeAsStringAsync(DDP + "sheetjs.xlsx", b64, { encoding: FileSystem.EncodingType.Base64 });
 ```
 
   </TabItem>