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

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Electron	demos/mobile	demos/grid	1	summary Embedded NodeJS + Chromium

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

The NodeJS Module 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.

Complete Example (click to show)

This demo includes a drag-and-drop box as well as a file input box, mirroring the SheetJS Data Preview Live Demo

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 : project structure
• main.js : main process script
• index.html : window page
• 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:

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:

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/

Writing Files

XLSX.writeFile writes workbooks to the file system. showSaveDialog shows a Save As dialog and returns the selected file name:

/* 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:

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:

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

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

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 applies to DIV elements on the page.

For example, assuming a DIV on the page:

<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:

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 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:

/* 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:

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.

:::