docs.sheetjs.com/docz/docs/03-demos/03-desktop/01-electron.md

---
title: Electron
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  summary: Embedded NodeJS + Chromium
---

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

The [NodeJS Module](/docs/getting-started/installation/nodejs) can be imported
from the main or the renderer thread.

Electron presents a `fs` module.  The `require('xlsx')` call loads the CommonJS
module, so `XLSX.readFile` and `XLSX.writeFile` work in the renderer thread.

This demo was tested on 2022 November 07 with Electron 21.2.2 on `darwin-x64`.

<details><summary><b>Complete Example</b> (click to show)</summary>

This demo includes a drag-and-drop box as well as a file input box, mirroring
the [SheetJS Data Preview Live Demo](https://oss.sheetjs.com/sheetjs/)

The core data in this demo is an editable HTML table.  The readers build up the
table using `sheet_to_html` (with `editable:true` option) and the writers scrape
the table using `table_to_book`.

The demo project is wired for `electron-forge` to build the standalone binary.

1) Download the demo files:

- [`package.json`](pathname:///electron/package.json) : project structure
- [`main.js`](pathname:///electron/main.js) : main process script
- [`index.html`](pathname:///electron/index.html) : window page
- [`index.js`](pathname:///electron/index.js) : script loaded in render context

:::caution

Right-click each link and select "Save Link As...".  Left-clicking a link will
try to load the page in your browser.  The goal is to save the file contents.

:::

2) Run `npm install` to install dependencies.

3) To verify the app works, run in the test environment:

```bash
npx -y electron .
```

The app will show and you should be able to verify reading and writing by using
the relevant buttons to open files and clicking the export button.

4) To build a standalone app, run the builder:

```bash
npm run make
```

This will generate the standalone app in the `out\sheetjs-electron-...` folder.
For a recent Intel Mac, the path will be `out/sheetjs-electron-darwin-x64/`

</details>

### Writing Files

[`XLSX.writeFile`](/docs/api/write-options) writes workbooks to the file system.
`showSaveDialog` shows a Save As dialog and returns the selected file name:

```js
/* from the renderer thread */
const electron = require('@electron/remote');

/* this function will show the save dialog and try to write the workbook */
async function exportFile(workbook) {
  /* show Save As dialog */
  const result = await electron.dialog.showSaveDialog({
    title: 'Save file as',
    filters: [{
      name: "Spreadsheets",
      extensions: ["xlsx", "xls", "xlsb", /* ... other formats ... */]
    }]
  });
  /* write file */
  // highlight-next-line
  XLSX.writeFile(workbook, result.filePath);
}
```

:::note

In older versions of Electron, `showSaveDialog` returned the path directly:

```js
var dialog = require('electron').remote.dialog;

function exportFile(workbook) {
  var result = dialog.showSaveDialog();
  XLSX.writeFile(workbook, result);
}
```

:::

### Reading Files

Electron offers 3 different ways to read files, two of which use Web APIs.

**File Input Element**

File input elements automatically map to standard Web APIs.

For example, assuming a file input element on the page:

```html
<input type="file" name="xlfile" id="xlf" />
```

The event handler would process the event as if it were a web event:

```js
async function handleFile(e) {
  const file = e.target.files[0];
  const data = await file.arrayBuffer();
  /* data is an ArrayBuffer */
  const workbook = XLSX.read(data);

  /* DO SOMETHING WITH workbook HERE */
}
document.getElementById("xlf").addEventListener("change", handleFile, false);
```

**Drag and Drop**

The [drag and drop snippet](/docs/solutions/input#example-user-submissions)
applies to DIV elements on the page.

For example, assuming a DIV on the page:

```html
<div id="drop">Drop a spreadsheet file here to see sheet data</div>
```

The event handler would process the event as if it were a web event:

```js
async function handleDrop(e) {
  e.stopPropagation();
  e.preventDefault();

  const file = e.dataTransfer.files[0];
  const data = await file.arrayBuffer();
  /* data is an ArrayBuffer */
  const workbook = XLSX.read(data);

  /* DO SOMETHING WITH workbook HERE */
}
document.getElementById("drop").addEventListener("drop", handleDrop, false);
```

**Electron API**

[`XLSX.readFile`](/docs/api/parse-options) reads workbooks from the file system.
`showOpenDialog` shows a Save As dialog and returns the selected file name.
Unlike the Web APIs, the `showOpenDialog` flow can be initiated by app code:

```js
/* from the renderer thread */
const electron = require('@electron/remote');

/* this function will show the open dialog and try to parse the workbook */
async function importFile() {
  /* show Save As dialog */
  const result = await electron.dialog.showOpenDialog({
    title: 'Select a file',
    filters: [{
      name: "Spreadsheets",
      extensions: ["xlsx", "xls", "xlsb", /* ... other formats ... */]
    }]
  });
  /* result.filePaths is an array of selected files */
  if(result.filePaths.length == 0) throw new Error("No file was selected!");
  // highlight-next-line
  return XLSX.readFile(result.filePaths[0]);
}
```

:::note

In older versions of Electron, `showOpenDialog` returned the path directly:

```js
var dialog = require('electron').remote.dialog;

function importFile(workbook) {
  var result = dialog.showOpenDialog({ properties: ['openFile'] });
  return XLSX.readFile(result[0]);
}
```

:::

### Electron Breaking Changes

The first version of this demo used Electron 1.7.5.  The current demo includes
the required changes for Electron 19.2.2.

There are no Electron-specific workarounds in the library, but Electron broke
backwards compatibility multiple times.  A summary of changes is noted below.

:::caution

Electron 6.x changed the `dialog` API. Methods like `showSaveDialog` originally
returned an array of strings, but now returns a `Promise`.  This change was not
documented.

Electron 9.0.0 and later require the preference `nodeIntegration: true` in order
to `require('xlsx')` in the renderer process.

Electron 12.0.0 and later also require `worldSafeExecuteJavascript: true` and
`contextIsolation: true`.

Electron 14+ must use `@electron/remote` instead of `remote`.  An `initialize`
call is required to enable Developer Tools in the window.

:::