docs.sheetjs.com/docz/docs/03-demos/32-extensions/02-chromium.md

---
title: Chrome and Chromium
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---

:::note pass

This demo showcases Manifest V2 and Manifest V3 extensions. Chrome Web Store
will not accept new V2 extensions, but these can be sideloaded using the
"Load unpacked" extension option in Developer mode.

:::

The [SheetJS Standalone scripts](/docs/getting-started/installation/standalone)
can be integrated in a Chromium extension.

This demo includes examples for exporting bookmarks from a popup and scraping
tables with a content script and a background script.

[The demo](#demo) includes unpacked extensions for Manifest V2 and Manifest V3.

:::note

This demo was last tested on 2023 October 14 against Chrome 117.

:::

## Loading SheetJS Scripts

SheetJS libraries should be bundled in the extension. For path purposes, it is
strongly recommended to place `xlsx.full.min.js` in the root folder.

#### Popup Pages

In Manifest V2 and Manifest V3 extensions, popup pages can load the standalone
script using a normal `<script>` tag:

```html
<script type="text/javascript" src="xlsx.full.min.js"></script>
```

#### Content Scripts

In Manifest V2 and Manifest V3 extensions, the standalone script can be loaded
through the `content_scripts` field:

```js
  /* in manifest.json v2 or v3 */
  "content_scripts": [{
    "matches": ["<all_urls>"],
    "js": ["xlsx.full.min.js", "content.js"],
    "run_at": "document_end"
  }],
```

The `XLSX` global will be visible to other content scripts.

#### Background Scripts

In Manifest V2 extensions, if the standalone script is added as a background
script, other background scripts will be able to access the `XLSX` global!

```js
  /* in manifest.json v2 only! */
  "background": {
    "scripts": ["xlsx.full.min.js", "table.js"],
    "persistent": false
  },
```

In Manifest V3 extensions, background service workers can load the standalone
script through `importScripts`:

```js
/* assuming background script is in the same folder as xlsx.full.min.js */
importScripts("./xlsx.full.min.js");
// now XLSX will be available
```

## Relevant Operations

The official documentation covers details including required permissions.

### Generating Downloads

#### Manifest V2

The `writeFile` function works in a Chrome or Chromium extension:

```js
XLSX.writeFile(wb, "export.xlsx");
```

Under the hood, it uses the `chrome.downloads` API.  `"downloads"` permission
should be set in `manifest.json`.

#### Manifest V3

In a background service worker, `URL.createObjectURL` is unavailable. Instead,
`XLSX.write` can generate a Base64 string for a synthetic URL:

```js
/* generate Base64 string */
const b64 = XLSX.write(wb, {bookType: "xlsx", type: "base64"});
chrome.downloads.download({
  /* make a base64 url manually */
  url: `data:application/octet-stream;base64,${b64}`,
  filename: `SheetJSTables.xlsx`
});
```

### Content Script Table Scraping

`table_to_book` and `table_to_sheet` can help build workbooks from DOM tables:

```js
var tables = document.getElementsByTagName("table");
var wb = XLSX.utils.book_new();
for(var i = 0; i < tables.length; ++i) {
  var ws = XLSX.utils.table_to_sheet(tables[i]);
  XLSX.utils.book_append_sheet(wb, ws, "Table" + i);
}
```

## Demo

The demo extension includes multiple features to demonstrate sample usage.
Production extensions should include proper error handling.

<details open><summary><b>Testing Unpacked Extension</b> (click to hide)</summary>

1) Download the zip for the desired Manifest version:

- [Manifest V2](pathname:///chromium/SheetJSChromiumUnpackedV2.zip)
- [Manifest V3](pathname:///chromium/SheetJSChromiumUnpackedV3.zip)

2) Open `chrome://extensions/` in the browser and enable Developer mode

3) Drag and drop the downloaded zip file into the window.

</details>

### Bookmark Exporter

<details open><summary><b>Testing</b> (click to hide)</summary>

0) Go to <https://sheetjs.com> and create a bookmark in the browser.

1) Click the Extensions icon (puzzle icon to the right of the address bar) and
select "SheetJS Demo".

2) If a small popup is not displayed, click on the SheetJS icon

3) Click "Export Bookmarks" and click "Save". Open the downloaded file!

</details>

```mermaid
sequenceDiagram
  actor U as User
  participant P as Popup
  participant A as Chromium
  U->>P: click icon
  P->>A: `chrome.bookmarks.getTree`
  A->>P: bookmark tree
  Note over P: walk tree
  Note over P: make workbook
  P->>U: `XLSX.writeFile`
```

`chrome.bookmarks` API enables bookmark tree traversal.  The "Export Bookmarks"
button in the extension pop-up recursively walks the bookmark tree, pushes the
bookmark URLs into a data array, and exports into a simple spreadsheet.

```js
/* walk the bookmark tree */
function recurse_bookmarks(data, tree) {
  if(tree.url) data.push({Name: tree.title, Location: tree.url});
  (tree.children||[]).forEach(function(child) { recurse_bookmarks(data, child); });
}

/* get bookmark data */
chrome.bookmarks.getTree(function(res) {
  /* load into an array */
  var data = [];
  res.forEach(function(t) { recurse_bookmarks(data, t); });

  /* create worksheet */
  var ws = XLSX.utils.json_to_sheet(data, { header: ['Name', 'Location'] });

  /* create workbook and export */
  var wb = XLSX.utils.book_new();
  XLSX.utils.book_append_sheet(wb, ws, 'Bookmarks');
  XLSX.writeFile(wb, "bookmarks.xlsx");
});
```

### Table Exporter

<details open><summary><b>Testing</b> (click to hide)</summary>

1) Go to <https://sheetjs.com/demo/table>

2) Right-click anywhere in the page and select "SheetJS Demo" > "Export All Tables in Page"

3) Save and open the downloaded file!

</details>

The background script configures a context menu with the option to export data.
The flow diagrams show the data flow when the user chooses to export. They
differ in the denouement

```mermaid
sequenceDiagram
  actor U as User
  participant P as Background Script
  participant A as Content Script
  U->>P: Context Click > "Export"
  Note over P: Query for active tab
  P->>A: Ask active tab for data
  Note over A: `table_to_sheet`
  Note over A: generate workbook
  A->>P: workbook object
  Note over U,A: ... different denouement for Manifest V2 / V3 extensions ...
```

#### Manifest V2

For Manifest V2 extensions, `XLSX.writeFile` just works:

```mermaid
sequenceDiagram
  actor U as User
  participant P as Background Script
  Note over P,U: ... background script received workbook ...
  P->>U: `XLSX.writeFile` download
```

#### Manifest V3

For Manifest V3 extensions, since `URL.createObjectURL` is not available in
background service workers, a synthetic URL is created:

```mermaid
sequenceDiagram
  actor U as User
  participant P as Background Script
  Note over P,U: ... background script received workbook ...
  Note over P: `XLSX.write` Base64
  Note over P: Create Data URL
  P->>U: `chrome.downloads.download`
```