---
title: NativeScript
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sidebar_position: 2
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summary: JS + Native Elements
---
import current from '/version.js';
import CodeBlock from '@theme/CodeBlock';
The [NodeJS Module](/docs/getting-started/installation/nodejs) can be imported
from the main entrypoint or any script in the project.
The "Complete Example" creates an app that looks like the screenshots below:
## Integration Details
The discussion covers the NativeScript + Angular integration. Familiarity with
Angular and TypeScript is assumed.
The `@nativescript/core/file-system` package provides classes for file access.
The `File` class does not support binary data, but the file access singleton
from `@nativescript/core` does support reading and writing `ArrayBuffer`.
Reading and writing data require a URL. The following snippet searches typical
document folders for a specified filename:
```ts
import { Folder, knownFolders, path } from '@nativescript/core/file-system';
function get_url_for_filename(filename: string): string {
const target: Folder = knownFolders.documents() || knownFolders.ios.sharedPublic();
return path.normalize(target.path + "///" + filename);
}
```
### Reading Local Files
`getFileAccess().readBufferAsync` can read data:
```ts
import { getFileAccess } from '@nativescript/core';
import { read } from 'xlsx';
/* find appropriate path */
const url = get_url_for_filename("SheetJSNS.xls");
/* get data */
const ab: ArrayBuffer = await getFileAccess().readBufferAsync(url);
/* read workbook */
const wb = read(ab);
```
### Writing Local Files
`getFileAccess().writeBufferAsync` can write data. iOS supports `Uint8Array`
directly but Android requires a true array of numbers:
```ts
import { getFileAccess } from '@nativescript/core';
import { write } from 'xlsx';
/* find appropriate path */
const url = get_url_for_filename("SheetJSNS.xls");
/* generate Uint8Array */
const u8: Uint8Array = write(wb, { bookType: 'xls', type: 'binary' });
/* attempt to save Uint8Array to file */
await getFileAccess().writeBufferAsync(url, global.isAndroid ? (Array.from(u8) as any) : u8);
```
### Fetching Remote Files
`getFile` from `@nativescript/core/http` can download files. After storing the
file in a temporary folder, `getFileAccess().readBufferAsync` can read the data:
```ts
import { knownFolders, path, getFileAccess } from '@nativescript/core'
import { getFile } from '@nativescript/core/http';
import { read } from 'xlsx';
/* generate temporary path for the new file */
const temp: string = path.join(knownFolders.temp().path, "pres.xlsx");
/* download file */
const file = await getFile("https://sheetjs.com/pres.xlsx", temp)
/* get data */
const ab: ArrayBuffer = await getFileAccess().readBufferAsync(file.path);
/* read workbook */
const wb = read(ab);
```
## Demo
:::note
This demo was tested on an Intel Mac on 2023 May 21. NativeScript version
(as verified with `ns --version`) is `8.5.3`.
The iOS simulator runs iOS 16.2 on an iPhone 14 Pro Max.
The Android simulator runs Android 12.0 (S) API 31 on a Pixel 3.
:::
0) Follow the official Environment Setup instructions
### Base Project
1) Create a skeleton NativeScript + Angular app:
```bash
ns create SheetJSNS --ng
```
2) Launch the app in the iOS simulator to verify that the demo built properly:
```bash
cd SheetJSNS
ns run ios
```
(this may take a while)
Once the simulator launches and the test app is displayed, end the script by
selecting the terminal and entering the key sequence `CTRL + C`
3) From the project folder, install the library:
{`\
npm i --save https://cdn.sheetjs.com/xlsx-${current}/xlsx-${current}.tgz`}
4) To confirm the library was loaded, change the title to show the version. The
differences are highlighted.
`src/app/item/items.component.ts` should import the version string:
```ts title="src/app/item/items.component.ts"
// highlight-next-line
import { version } from 'xlsx';
import { Component, OnInit } from '@angular/core'
// ...
export class ItemsComponent implements OnInit {
items: Array
// highlight-next-line
version = `SheetJS - ${version}`;
constructor(private itemService: ItemService) {}
// ...
```
`src/app/item/items.component.html` should use the version in the title:
```xml title="src/app/item/items.component.html"
```
Relaunch the app with `ns run ios` and the title bar should show the version.
### Local Files
5) Add the Import and Export buttons to the template:
```xml title="src/app/item/items.component.html"
```
```ts title="src/app/item/items.component.ts"
// highlight-start
import { version, utils, read, write } from 'xlsx';
import { Dialogs, getFileAccess } from '@nativescript/core';
import { Folder, knownFolders, path } from '@nativescript/core/file-system';
// highlight-end
import { Component, OnInit } from '@angular/core'
import { Item } from './item'
import { ItemService } from './item.service'
// highlight-start
function get_url_for_filename(filename: string): string {
const target: Folder = knownFolders.documents() || knownFolders.ios.sharedPublic();
return path.normalize(target.path + "///" + filename);
}
// highlight-end
@Component({
selector: 'ns-items',
templateUrl: './items.component.html',
})
export class ItemsComponent implements OnInit {
items: Array
version: string = `SheetJS - ${version}`;
constructor(private itemService: ItemService) {}
ngOnInit(): void {
this.items = this.itemService.getItems()
}
// highlight-start
/* Import button */
async import() {
}
/* Export button */
async export() {
}
// highlight-end
}
```
Restart the app process and two buttons should show up at the top:
6) Implement import and export by adding the highlighted lines:
```ts title="src/app/item/items.component.ts"
/* Import button */
async import() {
// highlight-start
/* find appropriate path */
const url = get_url_for_filename("SheetJSNS.xls");
try {
await Dialogs.alert(`Attempting to read from SheetJSNS.xls at ${url}`);
/* get data */
const ab: ArrayBuffer = await getFileAccess().readBufferAsync(url);
/* read workbook */
const wb = read(ab);
/* grab first sheet */
const wsname: string = wb.SheetNames[0];
const ws = wb.Sheets[wsname];
/* update table */
this.items = utils.sheet_to_json(ws);
} catch(e) { await Dialogs.alert(e.message); }
// highlight-end
}
/* Export button */
async export() {
// highlight-start
/* find appropriate path */
const url = get_url_for_filename("SheetJSNS.xls");
try {
/* create worksheet from data */
const ws = utils.json_to_sheet(this.items);
/* create workbook from worksheet */
const wb = utils.book_new();
utils.book_append_sheet(wb, ws, "Sheet1");
/* generate Uint8Array */
const u8: Uint8Array = write(wb, { bookType: 'xls', type: 'buffer' });
/* attempt to save Uint8Array to file */
await getFileAccess().writeBufferAsync(url, global.isAndroid ? (Array.from(u8) as any) : u8);
await Dialogs.alert(`Wrote to SheetJSNS.xls at ${url}`);
} catch(e) { await Dialogs.alert(e.message); }
// highlight-end
}
```
### iOS
Relaunch the app with `ns run ios`
The app can be tested with the following sequence in the simulator:
- Tap "Export File". A dialog will print where the file was written
- Open the file with a spreadsheet editor.
After the header row, insert a row with cell A2 = 0, B2 = SheetJS, C2 = Library:
```
id | name | role
0 | SheetJS | Library
1 | Ter Stegen | Goalkeeper
3 | Piqué | Defender
...
```
Restart the app after saving the file.
- Tap "Import File". A dialog will print the path of the file that was read.
The first item in the list will change:
### Android
Launch the app with `ns run android`. If the app does not automatically launch,
manually open the `SheetJSNS` app.
The app can be tested with the following sequence in the simulator:
- Tap "Export File". A dialog will print where the file was written. Typically
the URL is `/data/user/0/org.nativescript.SheetJSNS/files/SheetJSNS.xls`
- Pull the file from the simulator:
```bash
adb root
adb pull /data/user/0/org.nativescript.SheetJSNS/files/SheetJSNS.xls SheetJSNS.xls
```
- Open `SheetJSNS.xls` with a spreadsheet editor.
After the header row, insert a row with cell A2 = 0, B2 = SheetJS, C2 = Library:
```
id | name | role
0 | SheetJS | Library
1 | Ter Stegen | Goalkeeper
3 | Piqué | Defender
...
```
- Push the file back to the simulator:
```bash
adb push SheetJSNS.xls /data/user/0/org.nativescript.SheetJSNS/files/SheetJSNS.xls
```
- Tap "Import File". A dialog will print the path of the file that was read.
The first item in the list will change.
### Fetching Files
7) In `src/app/item/items.component.ts`, make `ngOnInit` asynchronous:
```ts title="src/app/item/items.component.ts"
async ngOnInit(): Promise {
this.items = await this.itemService.getItems()
}
```
8) Replace `item.service.ts` with the following:
```ts title="src/app/item/item.service.ts"
import { Injectable } from '@angular/core'
import { knownFolders, path, getFileAccess } from '@nativescript/core'
import { getFile } from '@nativescript/core/http';
import { read, utils } from 'xlsx';
import { Item } from './item'
interface IPresident { Name: string; Index: number };
@Injectable({ providedIn: 'root' })
export class ItemService {
private items: Array;
async getItems(): Promise> {
/* fetch https://sheetjs.com/pres.xlsx */
const temp: string = path.join(knownFolders.temp().path, "pres.xlsx");
const ab = await getFile("https://sheetjs.com/pres.xlsx", temp)
/* read the temporary file */
const wb = read(await getFileAccess().readBufferAsync(ab.path));
/* translate the first worksheet to the required Item type */
const data = utils.sheet_to_json(wb.Sheets[wb.SheetNames[0]]);
return this.items = data.map((pres, id) => ({id, name: pres.Name, role: ""+pres.Index} as Item));
}
getItem(id: number): Item {
return this.items.filter((item) => item.id === id)[0]
}
}
```
Relaunching the app in iOS or Android simulator should show Presidential data.