--- title: Excel JavaScript API pagination_prev: demos/cloud/index pagination_next: demos/bigdata/index sidebar_custom_props: summary: Add new data import functionality to Excel by integrating SheetJS in custom JavaScript user-defined functions and extensions. --- import current from '/version.js'; import CodeBlock from '@theme/CodeBlock'; :::info pass This demo focuses on the Excel JavaScript API. For reading and writing Excel spreadsheets, [other demos](/docs/demos/) cover a wide variety of use cases and deployments. ::: [SheetJS](https://sheetjs.com) is a JavaScript library for reading and writing data from spreadsheets. Office 2016 introduced a JavaScript API for interacting with the application. It offers solutions for custom functions as well as task panes. Excel currently does not provide support for working with Apple Numbers files and some legacy file formats. SheetJS fills the gap. In the ["Complete Demo"](#complete-demo), we'll create a new custom function `SHEETJS.EXTERN()` which tries to fetch an external spreadsheet and insert the data into the worksheet. ![`SHEETJS.EXTERN` output](pathname:///xlapi/xlfetch.png) :::note Tested Deployments This demo was last tested on 2024 August 11 against Excel 365 (version 2407). ::: :::caution Excel Bugs There was a binary data bug affecting `fetch` and Excel. It was resolved in version 2303. It is strongly encouraged to upgrade to the latest version of Excel 365 before running the demo. ::: :::danger Telemetry The Office Add-in CLI collects telemetry by default. It can be disabled: ```js npx office-addin-usage-data off ``` The setting can be verified by running: ```js npx office-addin-usage-data list ``` ::: ## Integration Details The [SheetJS NodeJS module](/docs/getting-started/installation/nodejs) can be imported from scripts in an Excel Custom Functions project. The [`sheet_to_json`](/docs/api/utilities/array#array-output) helper function can generate arrays of arrays of values based on the worksheet data. Excel custom functions transparently treat arrays of arrays as Dynamic Arrays. This example fetches a file using the `fetch` API, parses the binary data using the SheetJS `read`[^1] method and returns data from the first worksheet. ```mermaid flowchart LR url[(Remote\nFile)] ab[(File\nBytes)] subgraph SheetJS Structures wb(((SheetJS\nWorkbook))) ws((SheetJS\nWorksheet)) end aoo[[Array of\nObjects]] xl>Excel\nWorksheet] url --> |fetch\narrayBuffer| ab ab --> |read\n\n| wb wb --> |wb.Sheets\nselect sheet| ws ws --> |sheet_to_json\n\n| aoo aoo --> |return\nExcel| xl linkStyle 1,2,3 color:blue,stroke:blue; ``` ```js title="src\functions\functions.js" const XLSX = require("xlsx"); /** * Download file and write data * @customfunction * @param {string} url URL to fetch and parse * @returns {any[][]} Worksheet data */ export async function extern(url) { try { /* Fetch Data */ const res = await fetch(url); /* Get Data */ const ab = await res.arrayBuffer(); /* Parse Data */ const wb = XLSX.read(ab); /* Translate Data */ const ws = wb.Sheets[wb.SheetNames[0]]; // get first worksheet const aoa = XLSX.utils.sheet_to_json(ws, { header: 1 }); // array of arrays /* Return Data */ return aoa; } catch(e) { return [[e.message || e]]; } // pass error back to Excel } ``` ## Complete Demo 0) Clear the functions cache. For the tested version of Excel: - Open File Explorer - Select the address bar and enter `%LOCALAPPDATA%\Microsoft\Office\16.0\Wef` - Delete the `CustomFunctions` folder (if it exists) and empty Recycle Bin. :::caution pass **This will delete all custom functions associated with the user account!** To preserve the custom functions on the user account, rename the existing folder to `CustomFunctionsBackup` before testing and rename back to `CustomFunctions` after testing is finished. ::: 1) Install [NodeJS LTS](https://nodejs.org/en/download/). 2) After installing NodeJS, launch a new PowerShell window. 3) Disable telemetry: ```bash npx office-addin-usage-data off ``` 4) Install dependencies: ```bash npm i -g yo bower generator-office ``` ### Creating a new Add-in 5) Run the generator: ```bash npx yo office ``` The generator will ask a few questions: - "Choose a project type": "Excel Custom Functions using a Shared Runtime" - "Choose a script type": "JavaScript", - "What do you want to name your add-in?": "SheetJSImport" The generator will create the project and install dependencies. 6) Start the development process: ```bash cd SheetJSImport npm run build npm start ``` If prompted to `Allow localhost loopback for Microsoft Edge WebView`, type N and press Enter. If prompted to install "Developer CA for Microsoft Office Add-ins" certificate, select "Yes" If Windows Firewall prompts to allow Node.js on private networks, select "Yes" A new terminal window running NodeJS will be created. Keep the window open. A new Excel window with the loaded add-in will launch. :::caution pass In some tests, the taskpane showed an error: ``` Script error. ``` [Webview2](https://developer.microsoft.com/en-us/microsoft-edge/webview2/) should be installed manually. ::: 7) In `manifest.xml` , search for `Functions.Namespace` . There will be an XML element with name `bt:String`. Change the `DefaultValue` attribute to `SHEETJS`: ```xml title="manifest.xml (change highlighted line)" // highlight-next-line ``` 8) Close the Excel window and the terminal window. Do not save the XLSX file. 9) In the PowerShell window, start the development process again: ```bash npm start ``` ### Integrating the SheetJS Library 10) Install the SheetJS library in the project {`\ npm i --save https://cdn.sheetjs.com/xlsx-${current}/xlsx-${current}.tgz`} 11) Replace `src\functions\functions.js` with the following: ```js title="src\functions\functions.js" var XLSX = require("xlsx"); /** * Print SheetJS Library Version * @customfunction * @returns {string[][]} The SheetJS Library Version. */ export function version() { return [[XLSX.version]]; } ``` 12) Close the terminal window and the Excel window. Do not save the Excel file. 13) In the PowerShell window, start the development process again: ```bash npm start ``` 14) In the new Excel window, enter the formula `=SHEETJS.VERSION()` in cell `E1`. You should see something similar to the following screenshot: ![`SHEETJS.VERSION` output](pathname:///xlapi/xlvers.png) This indicates that the SheetJS library has been loaded. ### Fetching Files from the Internet 15) Add the following code snippet to `src\functions\functions.js` and save: ```js title="src\functions\functions.js (add to end)" /** * Download file and write data * @customfunction * @param {string} url URL to fetch and parse * @returns {any[][]} Worksheet data */ export async function extern(url) { try { /* Fetch Data */ const res = await fetch(url); /* Get Data */ const ab = await res.arrayBuffer(); /* Parse Data */ var wb = XLSX.read(ab); /* get and return data */ var ws = wb.Sheets[wb.SheetNames[0]]; // get first worksheet var aoa = XLSX.utils.sheet_to_json(ws, { header: 1 }); // get data as array of arrays return aoa; } catch(e) { return [[e.message || e]]; } // pass error back to Excel } ``` 16) Close the terminal window and the Excel window (do not save the Excel file). 17) In the PowerShell window, start the development process again: ```bash npm start ``` 18) Enter the text `https://docs.sheetjs.com/pres.numbers` in cell `D1`. Enter the formula `=SHEETJS.EXTERN(D1)` in cell `D2` and press Enter. Excel should pull in the data and generate a dynamic array. The worksheet should match the screenshot at the top of this page. :::tip pass [SheetJS Pro](https://sheetjs.com/pro) offers additional features that can be used in Excel Custom Functions and Add-ins. ::: [^1]: See [`read` in "Reading Files"](/docs/api/parse-options)