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+docs/** linguist-generated
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mv docz/build/ docs
cp CNAME docs
-.PHONY: server
+.PHONY: serve
serve:
cd docs; python -mSimpleHTTPServer; cd -
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+---
+sidebar_position: 4
+---
+
+# Excel JavaScript API
+
+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.
+
+This demo creates a new custom function to add much-needed functionality:
+
+- `SHEETJS.EXTERN()` tries to fetch an external spreadsheet and insert the data
+into the worksheet.
+
+This demo focuses on the basic mechanics. Advanced topics like Excel Custom
+Function parameters are covered in the official Office JavaScript API docs.
+SheetJS worksheet metadata and other properties are covered in this doc site.
+
+## Creating a new Add-in
+
+Initial Platform Setup (click to show)
+
+The tool for generating Office Add-ins depends on NodeJS and various libraries.
+[Install NodeJS](https://nodejs.org/) and the required dependencies:
+
+```powershell
+npm install -g yo bower generator-office
+```
+
+Creating a new Project (click to show)
+
+Run `yo office` from the command line. It will ask a few questions.
+
+- "Choose a project type": "Excel Custom Functions Add-in project"
+
+- "Choose a script type": "JavaScript",
+
+- "What do you want to name your add-in?": "SheetJSImport"
+
+You will see a screen like
+
+```
+? Choose a project type: Excel Custom Functions Add-in project
+? Choose a script type: JavaScript
+? What do you want to name your add-in? SheetJSImport
+
+----------------------------------------------------------------------------------
+
+ Creating SheetJSImport add-in for Excel using JavaScript and Excel-functions
+at C:\Users\SheetJS\Documents\SheetJSImport
+
+----------------------------------------------------------------------------------
+```
+
+It helpfully prints out the next steps:
+
+```powershell
+cd SheetJSImport
+npm run build
+npm start
+```
+
+If you have [VSCodium](https://vscodium.com/) installed, the folder can be opened with
+
+```powershell
+codium .
+```
+
+Excel bug related to `fetch` (click to show)
+
+`fetch` is available to custom functions:
+
+```js
+async function extern() {
+ try {
+ const url = "https://sheetjs.com/pres.numbers"; // URL to download
+ const res = await fetch(url); // fetch data
+ const ab = await res.arrayBuffer(); // get data as an array buffer
+
+ // DO SOMETHING WITH THE DATA HERE
+
+ } catch(e) { return e; } // pass error back to Excel
+}
+```
+
+When fetching data, functions typically receive an `ArrayBuffer` which stores
+the file data. This is readily parsed with `read`:
+
+```js
+var wb = XLSX.read(ab); // parse workbook
+```
+
+**This is how it should work**.
+
+[There are outstanding bugs](https://github.com/OfficeDev/office-js/issues/2186)
+
+For the purposes of this demo, a Base64-encoded file will be used. The
+workaround involves fetching that Base64 file, getting the text, and parsing
+with the [`base64` type:](../../api/parse-options#input-type)
+
+```js
+async function extern() {
+ try {
+ const url = "https://sheetjs.com/pres.numbers.b64"; // URL to download
+ const res = await fetch(url); // fetch data
+ const text = await res.text(); // get data as an array buffer
+
+ var wb = XLSX.read(text, { type: "base64" });
+ // DO SOMETHING WITH THE DATA HERE
+
+ } catch(e) { return e; } // pass error back to Excel
+}
+```
+
+Base64-encoded files can be generated with PowerShell:
+
+```powershell
+[convert]::ToBase64String([System.IO.File]::ReadAllBytes((Resolve-Path "path\to\file"))) > file.b64
+```
+
+Interactive Translator (click to show)
+Function Name Translator (click to show)
```jsx live
/* The live editor requires this function wrapper */
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