--- title: Packing Sheets with Webpack sidebar_label: Webpack pagination_prev: demos/net/index pagination_next: demos/mobile/index sidebar_custom_props: type: bundler --- import current from '/version.js'; import CodeBlock from '@theme/CodeBlock'; [Webpack](https://webpack.js.org/) is a modern build tool for generating static sites. It has a robust JavaScript-powered plugin system[^1] [SheetJS](https://sheetjs.com) is a JavaScript library for reading and writing data from spreadsheets. This demo uses Webpack and SheetJS to pull data from a spreadsheet and display the content in an HTML table. We'll explore how to load SheetJS in a Webpack 5 Asset Plugin and generate data for use in webpages. The ["Webpack 5 Demo"](#webpack-5-demo) creates a complete website powered by a XLSX spreadsheet. :::info pass This demo covers static asset imports. For processing files in the browser, the ["Bundlers" demo](/docs/demos/frontend/bundler/webpack) includes an example of importing the SheetJS library in a browser script. ::: ## Webpack 5 Asset Module Webpack 5 supports asset modules. With a special option, the loader will receive NodeJS Buffers that can be parsed. The dev server will even watch the files and reload the page in development mode! The [SheetJS NodeJS module](/docs/getting-started/installation/nodejs) can be imported from Webpack loader scripts. The following diagram depicts the workbook waltz: ```mermaid flowchart LR file[(workbook\nfile)] subgraph SheetJS operations buffer(NodeJS\nBuffer) aoo(array of\nobjects) end html{{HTML\nTABLE}} file --> |webpack.config.js\ncustom rule| buffer buffer --> |sheetjs-loader.js\ncustom plugin| aoo aoo --> |src/index.js\nfrontend code| html ``` ### Webpack Config The Webpack configuration is normally saved to `webpack.config.js`. #### Required Settings `module.rules` is an array of rule objects that controls module synthesis.[^2] For the SheetJS Webpack integration, the following properties are required: - `test` describes whether the rule is relevant. If the property is a regular expression, Webpack will test the filename against the `test` property. - `use` lists the loaders that will process files matching the `test`. The loaders are specified using the `loader` property of the loader object. The following example instructs Webpack to use the `sheetjs-loader.js` script when the file name ends in `.numbers` or `.xls` or `.xlsx` or `.xlsb`: ```js title="webpack.config.js (define loader)" // ... module.exports = { // ... module: { rules: [ // highlight-start { /* `test` matches file extensions */ test: /\.(numbers|xls|xlsx|xlsb)$/, /* use the loader script */ use: [ { loader: './sheetjs-loader' } ] } // highlight-end ] } }; ``` #### Recommended Settings It is strongly recommended to enable other Webpack features: - `resolve.alias` defines path aliases. If data files are stored in one folder, an alias ensures that each page can reference the files using the same name[^3]. - `devServer.hot` enables "hot module replacement"[^4], ensuring that pages will refresh in development mode when spreadsheets are saved. The following example instructs Webpack to treat `~` as the root of the project (so `~/data/pres.xlsx` refers to `pres.xlsx` in the data folder) and to enable live reloading: ```js title="webpack.config.js (other recommended settings)" // ... module.exports = { // ... // highlight-start resolve: { alias: { /* `~` root of the project */ "~": __dirname } }, // highlight-end // ... // highlight-start /* enable live reloading in development mode */ devServer: { static: './dist', hot: true } // highlight-end }; ``` ### SheetJS Loader The SheetJS loader script must be saved to the script referenced in the Webpack configuration (`sheetjs-loader.js`). As with [ViteJS](/docs/demos/static/vitejs), Webpack will interpret data as UTF-8 strings. This corrupts binary formats including XLSX and XLS. To suppress this behavior and instruct Webpack to pass a NodeJS `Buffer` object, the loader script must export a `raw` property that is set to `true`[^5]. The base export is expected to be the loader function. The loader receives the file bytes as a Buffer, which can be parsed with the SheetJS `read` method[^6]. `read` returns a SheetJS workbook object[^7]. The loader in this demo will parse the workbook, pull the first worksheet, and generate an array of row objects using the `sheet_to_json` method[^8]: ```js title="sheetjs-loader.js (Webpack loader)" const XLSX = require("xlsx"); function loader(content) { /* since `loader.raw` is true, `content` is a Buffer */ const wb = XLSX.read(content); /* pull data from first worksheet */ var data = XLSX.utils.sheet_to_json(wb.Sheets[wb.SheetNames[0]]); return `export default JSON.parse('${JSON.stringify(data)}')`; } /* ensure the function receives a Buffer */ loader.raw = true; /* export the loader */ module.exports = loader; ``` ### Asset Imports Spreadsheets can be imported using the plugin. Assuming `pres.xlsx` is stored in the `data` subfolder, `~/data/pres.xlsx` can be imported from any script: ```js title="src/index.js (main script)" import data from '~/data/pres.xlsx'; /* `data` is an array of objects from data/pres.xlsx */ const elt = document.createElement('div'); elt.innerHTML = "" + data.map((row) => ``).join("") + "
NameIndex
${row.Name} ${row.Index}
"; document.body.appendChild(elt); ``` ## Webpack 5 Demo :::note Tested Deployments This demo was last tested on 2024 April 06 against Webpack 5.91.0 ::: ### Initial Setup 0) Create a new skeleton project: ```bash mkdir sheetjs-wp5 cd sheetjs-wp5 npm init -y npm install webpack@5.91.0 webpack-cli@5.1.4 webpack-dev-server@5.0.4 --save mkdir -p dist mkdir -p src mkdir -p data ``` 1) Install the SheetJS NodeJS module: {`\ npm i --save https://cdn.sheetjs.com/xlsx-${current}/xlsx-${current}.tgz`} 2) Save the following to `dist/index.html`: ```html title="dist/index.html" SheetJS + Webpack 5 ``` 3) Save the following to `src/index.js`: ```js title="src/index.js" import data from '~/data/pres.xlsx'; const elt = document.createElement('div'); elt.innerHTML = "" + data.map((row) => ``).join("") + "
NameIndex
${row.Name} ${row.Index}
"; document.body.appendChild(elt); ``` 4) Save the following to `webpack.config.js`: ```js title="webpack.config.js" const path = require('path'); module.exports = { entry: './src/index.js', output: { filename: 'main.js', path: path.resolve(__dirname, 'dist'), }, devServer: { static: './dist', hot: true, }, resolve: { alias: { "~": __dirname } }, module: { rules: [ { test: /\.(numbers|xls|xlsx|xlsb)$/, use: [ { loader: './sheetjs-loader' } ] } ] } }; ``` 5) Save the following to `sheetjs-loader.js`: ```js title="sheetjs-loader.js" const XLSX = require("xlsx"); function loader(content) { /* since `loader.raw` is true, `content` is a Buffer */ const wb = XLSX.read(content); /* pull data from first worksheet */ var data = XLSX.utils.sheet_to_json(wb.Sheets[wb.SheetNames[0]]); return `export default JSON.parse('${JSON.stringify(data)}')`; } /* ensure the function receives a Buffer */ loader.raw = true; module.exports = loader; ``` 6) Download and save to the `data` folder: ```bash curl -L -o data/pres.xlsx https://sheetjs.com/pres.xlsx ``` ### Live Reload Test 7) Open the test file `data/pres.xlsx` in a spreadsheet editor like Excel. 8) Start the development server: ```bash npx webpack serve --mode=development ``` The terminal will print URLs for the development server: ``` [webpack-dev-server] Project is running at: [webpack-dev-server] Loopback: http://localhost:8080/ ``` 9) Open the `Loopback` address (`http://localhost:8080`) in a web browser. It should display a table of Presidents with "Name" and "Index" columns 10) Add a new row to the spreadsheet (set `A7` to "SheetJS Dev" and `B7` to 47) and save the file. After saving the file, the page should automatically refresh with the new data. ### Static Site Test 11) Stop Webpack and build the site: ```bash npx webpack --mode=production ``` The final site will be placed in the `dist` folder. 12) Start a local web server to host the `dist` folder: ```bash npx http-server dist ``` The command will print a list of URLs. 13) Open one of the URLs printed in the previous step (`http://localhost:8080`) and confirm that the same data is displayed. To verify that the page is independent of the spreadsheet, make some changes to the file and save. The page will not automatically update. To verify that the data was added to the page, append `main.js` to the URL (`http://localhost:8080/main.js`) and view the source. The source will include president names. It will not include SheetJS library references! [^1]: See ["Plugins"](https://webpack.js.org/concepts/plugins/) in the Webpack documentation. [^2]: See [`module.rules`](https://webpack.js.org/configuration/module/#modulerules) in the Webpack documentation. [^3]: See [`resolve.alias`](https://webpack.js.org/configuration/resolve/#resolvealias) in the Webpack documentation. [^4]: See ["Hot Module Replacement"](https://webpack.js.org/concepts/hot-module-replacement/) in the Webpack documentation. [^5]: See ["Raw" Loader](https://webpack.js.org/api/loaders/#raw-loader) in the Webpack documentation. [^6]: See [`read` in "Reading Files"](/docs/api/parse-options) [^7]: See ["Workbook Object"](/docs/csf/book) [^8]: See [`sheet_to_json` in "Utilities"](/docs/api/utilities/array#array-output)