--- title: Sheets in Svelte Sites sidebar_label: Svelte description: Build interactive websites with Svelte. Seamlessly integrate spreadsheets into your app using SheetJS. Bring Excel-powered workflows and data to the modern web. pagination_prev: demos/index pagination_next: demos/grid/index sidebar_position: 4 --- import current from '/version.js'; import CodeBlock from '@theme/CodeBlock'; [Svelte](https://svelte.dev/) is a JavaScript library for building user interfaces. [SheetJS](https://sheetjs.com) is a JavaScript library for reading and writing data from spreadsheets. This demo uses Svelte and SheetJS to process and generate spreadsheets. We'll explore how to load SheetJS in a Svelte component and compare common state models and data flow strategies. :::note pass This demo focuses on Svelte concepts. Other demos cover general deployments: - [Static Site Generation powered by SvelteKit](/docs/demos/static/svelte) - [iOS applications powered by CapacitorJS](/docs/demos/mobile/capacitor) - [Desktop application powered by Wails](/docs/demos/desktop/wails) ::: ## Installation [The "Frameworks" section](/docs/getting-started/installation/frameworks) covers installation with Yarn and other package managers. The library can be imported directly from Svelte files with: ```js import { read, utils, writeFile } from 'xlsx'; ``` ## Internal State The various SheetJS APIs work with various data shapes. The preferred state depends on the application. ### Array of Objects Typically, some users will create a spreadsheet with source data that should be loaded into the site. This sheet will have known columns. For example, our [presidents sheet](https://sheetjs.com/pres.xlsx) has "Name" / "Index" columns: ![`pres.xlsx` data](pathname:///pres.png) This naturally maps to an array of typed objects, as in the TS example below: ```ts import { read, utils } from 'xlsx'; interface President { Name: string; Index: number; } const f = await (await fetch("https://sheetjs.com/pres.xlsx")).arrayBuffer(); const wb = read(f); const data = utils.sheet_to_json<President>(wb.Sheets[wb.SheetNames[0]]); console.log(data); ``` `data` will be an array of objects: ```js [ { Name: "Bill Clinton", Index: 42 }, { Name: "GeorgeW Bush", Index: 43 }, { Name: "Barack Obama", Index: 44 }, { Name: "Donald Trump", Index: 45 }, { Name: "Joseph Biden", Index: 46 } ] ``` A component will typically map over the data. The following example generates a TABLE with a row for each President: ```html title="src/SheetJSSvelteAoO.svelte" <script> import { onMount } from 'svelte'; import { read, utils, writeFileXLSX } from 'xlsx'; /* the component state is an array of presidents */ let pres = []; /* Fetch and update the state once */ onMount(async() => { const f = await (await fetch("https://sheetjs.com/pres.xlsx")).arrayBuffer(); const wb = read(f); // parse the array buffer const ws = wb.Sheets[wb.SheetNames[0]]; // get the first worksheet // highlight-start pres = utils.sheet_to_json(ws); // generate objects and update state // highlight-end }); /* get state data and export to XLSX */ function exportFile() { // highlight-next-line const ws = utils.json_to_sheet(pres); const wb = utils.book_new(); utils.book_append_sheet(wb, ws, "Data"); writeFileXLSX(wb, "SheetJSSvelteAoO.xlsx"); } </script> <main> <table><thead><th>Name</th><th>Index</th></thead><tbody> <!-- highlight-start --> {#each pres as p}<tr> <td>{p.Name}</td> <td>{p.Index}</td> </tr>{/each} <!-- highlight-end --> </tbody><tfoot><td colSpan={2}> <button on:click={exportFile}>Export XLSX</button> </td></tfoot></table> </main> ``` <details open><summary><b>How to run the example</b> (click to show)</summary> :::note This demo was last run on 2023 August 27 using `svelte@4.2.0`. When running `npm create`, the package `create-vite@4.4.1` was installed. ::: 1) Run `npm create vite@latest sheetjs-svelte -- --template svelte-ts`. 2) Install the SheetJS dependency and start the dev server: <CodeBlock language="bash">{`\ cd sheetjs-svelte npm i npm i --save https://cdn.sheetjs.com/xlsx-${current}/xlsx-${current}.tgz npm run dev`} </CodeBlock> 3) Open a web browser and access the displayed URL (`http://localhost:5173`) 4) Replace `src/App.svelte` with the `src/SheetJSSvelteAoO.svelte` example. The page will refresh and show a table with an Export button. Click the button and the page will attempt to download `SheetJSSvelteAoA.xlsx`. There may be a delay since Vite will try to optimize the SheetJS library on the fly. 5) Build the site with `npm run build`, then test with `npx http-server dist`. Access `http://localhost:8080` with a web browser to test the bundled site. </details> ### HTML The main disadvantage of the Array of Objects approach is the specific nature of the columns. For more general use, passing around an Array of Arrays works. However, this does not handle merge cells well! The `sheet_to_html` function generates HTML that is aware of merges and other worksheet features. Svelte `@html` tag allows raw HTML strings: ```html title="src/SheetJSSvelteHTML.svelte" <script> import { onMount } from 'svelte'; import { read, utils, writeFileXLSX } from 'xlsx'; let html = ""; let tbl; /* Fetch and update the state once */ onMount(async() => { const f = await (await fetch("https://sheetjs.com/pres.xlsx")).arrayBuffer(); const wb = read(f); // parse the array buffer const ws = wb.Sheets[wb.SheetNames[0]]; // get the first worksheet // highlight-start html = utils.sheet_to_html(ws); // generate HTML and update state // highlight-end }); /* get state data and export to XLSX */ function exportFile() { // highlight-start const elt = tbl.getElementsByTagName("TABLE")[0]; const wb = utils.table_to_book(elt); // highlight-end writeFileXLSX(wb, "SheetJSSvelteHTML.xlsx"); } </script> <main> <button on:click={exportFile}>Export XLSX</button> <!-- highlight-start --> <div bind:this={tbl}>{@html html}</div> <!-- highlight-end --> </main> ``` <details open><summary><b>How to run the example</b> (click to show)</summary> :::note This demo was last run on 2023 August 27 using `svelte@4.2.0`. When running `npm create`, the package `create-vite@4.4.1` was installed. ::: 1) Run `npm create vite@latest sheetjs-svelte -- --template svelte-ts`. 2) Install the SheetJS dependency and start the dev server: <CodeBlock language="bash">{`\ cd sheetjs-svelte npm i npm i --save https://cdn.sheetjs.com/xlsx-${current}/xlsx-${current}.tgz npm run dev`} </CodeBlock> 3) Open a web browser and access the displayed URL (`http://localhost:5173`) 4) Replace `src/App.svelte` with the `src/SheetJSSvelteHTML.svelte` example. The page will refresh and show a table with an Export button. Click the button and the page will attempt to download `SheetJSSvelteHTML.xlsx`. There may be a delay since Vite will try to optimize the SheetJS library on the fly. 5) Build the site with `npm run build`, then test with `npx http-server dist`. Access `http://localhost:8080` with a web browser to test the bundled site. </details>