Sheets in VueJS Sites with NuxtJS

Nuxt Content is a file-based CMS for NuxtJS, enabling static-site generation and on-demand server rendering from data files.

SheetJS is a JavaScript library for reading and writing data from spreadsheets.

This demo uses NuxtJS and SheetJS to pull data from a spreadsheet and display the content in an HTML table.

There were breaking changes between VueJS 2.x and VueJS 3.x. Since many projects still use VueJS 2.x, this demo includes examples for both versions of VueJS.

The "Nuxt Content v1" section explores "parsers" for NuxtJS Content v1 (paired with VueJS 2.x and NuxtJS 2.x)

The "Nuxt Content v2" section explores "transformers" for NuxtJS Content v2 (paired with VueJS 3.x and NuxtJS 3.x)

This demo focuses on server-side processing with NuxtJS and VueJS.

The VueJS demo includes examples of NuxtJS sites that process spreadsheets in the browser.

Tested Deployments

This demo was tested in the following environments:

Nuxt Content	Nuxt	Date
`1.15.1`	`2.17.2`	2023-12-04
`2.9.0`	`3.8.2`	2023-12-04

Telemetry

Nuxt embeds telemetry. According to the docs, it can be disabled with:

npx nuxt telemetry disable

At the time the demo was last tested, this command did not work.

Disabling telemetry requires a few steps:

Set the environment variable NUXT_TELEMETRY_DISABLED to 1

Linux/MacOS
Windows

Add the following line to .profile, .bashrc and .zshrc:

export NUXT_TELEMETRY_DISABLED=1

Close and restart the Terminal to load the changes.

Type env in the search bar and select "Edit the system environment variables".

In the new window, click the "Environment Variables..." button.

In the new window, look for the "System variables" section and click "New..."

Set the "Variable name" to NUXT_TELEMETRY_DISABLED and the value to 1.

Click "OK" in each window (3 windows) and restart your computer.

A global setting should be added to .nuxtrc in the user home directory:

~/.nuxtrc

telemetry.enabled=false

For Nuxt 3 sites, set the telemetry option in the Nuxt config file (either nuxt.config.ts or nuxt.config.js):

nuxt.config.js
// ...
export default defineNuxtConfig({
  // @ts-ignore
  telemetry: false,
  // ...
})

Nuxt Content v1

Nuxt Content v1 is designed to work with NuxtJS v2 and VueJS v2.

The following diagram depicts the workbook waltz:

Installation

The SheetJS NodeJS Module can be imported from nuxt.config.js for build-time processing.

Custom Parser

Custom parsers receive the file content interpreted as UTF-8 strings. For binary formats including XLSX and XLS, the data is corrupt and cannot be used.

The workaround involves safely re-reading the spreadsheets.

The second argument passed to the parser is an object. The path property of the object is the path to the file.

The SheetJS readFile¹ method can locate and parse the spreadsheet files. The sheet_to_json² utility function can generate arrays of row objects for use in NuxtJS pages:

Custom Parser (in nuxt.config.js)
import { readFile, utils } from 'xlsx';

/* This will be called when the files change */
const parseSheet = (file, { path }) => {
  /* `path` is a path that can be read with `XLSX.readFile` */
  const wb = readFile(path);

  /* iterate through each worksheet name and generate row objects */
  const o = wb.SheetNames.map(name => ({
    name: name,
    data: utils.sheet_to_json(wb.Sheets[name])
  }));

  /* The final result must be stored in the `data` key of an object */
  return { data: o };
};

Configuration

Using content.extendParser³, Nuxt Content will use custom parsers.

The property is expected to be an object whose keys are file extensions (with the . before the extension) and whose values are custom parser functions.

The relevant part of the config is shown below. In this snippet, the custom parser parseSheet will be associated with XLSX, XLS and NUMBERS files:

nuxt.config.js
export default {
// ...

  // content.extendParser allows us to hook into the parsing step
  content: {
    extendParser: {
      // the keys are the extensions that will be matched.  The "." is required
      ".numbers": parseSheet,
      ".xlsx": parseSheet,
      ".xls": parseSheet,
      // can add other extensions like ".fods" as desired
    }
  },

// ...
}

Template Use

When a spreadsheet is placed in the content folder, Nuxt will find it. The data can be referenced in a view with asyncData. The name should not include the extension, so "sheetjs.numbers" would be referenced as "sheetjs":

Script section of .vue VueJS page
  async asyncData ({$content}) {
    return {
      // $content('sheetjs') will match files with extensions in nuxt.config.js
      data: await $content('sheetjs').fetch()
    };
  }

In the template, data.data is an array of objects. Each object has a name property for the worksheet name and a data array of row objects. This maps neatly with nested v-for⁴:

Template section of .vue VueJS page
  <!-- loop over the worksheets -->
  <div v-for="item in data.data" v-bind:key="item.name">
    <table>
      <!-- loop over the rows of each worksheet -->
      <tr v-for="row in item.data" v-bind:key="row.Index">
        <!-- here `row` is a row object generated from sheet_to_json -->
        <td>{{ row.Name }}</td>
        <td>{{ row.Index }}</td>
      </tr>
    </table>
  </div>

Nuxt Content Demo

For some older versions, parts of the Nuxt dependency tree did not support NodeJS version 20. EBADENGINE warnings were displayed during app creation:

npm WARN EBADENGINE Unsupported engine {
npm WARN EBADENGINE   package: '@nuxt/[email protected]',
npm WARN EBADENGINE   required: { node: '^14.18.0 || ^16.10.0 || ^17.0.0 || ...
npm WARN EBADENGINE   current: { node: 'v20.2.0', npm: '9.6.6' }
npm WARN EBADENGINE }

The recommended solution is to switch to Node 18.

Create a stock app:

npx [email protected] sheetjs-nuxt

When prompted, enter the following options:

Project name: press Enter (use default sheetjs-nuxt)
Programming language: press Down Arrow (TypeScript selected) then Enter
Package manager: select Npm and press Enter
UI framework: select None and press Enter
Nuxt.js modules: scroll to Content, select with Space, then press Enter
Linting tools: press Enter (do not select any Linting tools)
Testing framework: select None and press Enter
Rendering mode: select Universal (SSR / SSG) and press Enter
Deployment target: select Static (Static/Jamstack hosting) and press Enter
Development tools: press Enter (do not select any Development tools)
What is your GitHub username?: press Enter
Version control system: select None

The project will be configured and modules will be installed.

Install the SheetJS library and start the server:

cd sheetjs-nuxt
npm i --save https://cdn.sheetjs.com/xlsx-0.20.2/xlsx-0.20.2.tgz
npm run dev

When the build finishes, the terminal will display a URL like:

ℹ Listening on: http://localhost:64688/

The server is listening on that URL. Open the link in a web browser.

Download https://sheetjs.com/pres.xlsx and move to the content folder.

curl -L -o content/pres.xlsx https://sheetjs.com/pres.xlsx

Modify nuxt.config.js as follows:

Add the following to the top of the script:

import { readFile, utils } from 'xlsx';

// This will be called when the files change
const parseSheet = (file, { path }) => {
  // `path` is a path that can be read with `XLSX.readFile`
  const wb = readFile(path);
  const o = wb.SheetNames.map(name => ({ name, data: utils.sheet_to_json(wb.Sheets[name])}));
  return { data: o };
};

Look for the exported object. There should be a content property:

  // Content module configuration: https://go.nuxtjs.dev/config-content
  content: {},

Replace the property with the following definition:

  // content.extendParser allows us to hook into the parsing step
  content: {
    extendParser: {
      // the keys are the extensions that will be matched.  The "." is required
      ".numbers": parseSheet,
      ".xlsx": parseSheet,
      ".xls": parseSheet,
      // can add other extensions like ".fods" as desired
    }
  },

(If the property is missing, add it to the end of the exported object)

Replace pages/index.vue with the following:

pages/index.vue
<!-- sheetjs (C) 2013-present  SheetJS -- https://sheetjs.com -->
<template><div>
  <div v-for="item in data.data" v-bind:key="item.name">
    <h2>{{ item.name }}</h2>
    <table><thead><tr><th>Name</th><th>Index</th></tr></thead><tbody>
      <tr v-for="row in item.data" v-bind:key="row.Index">
        <td>{{ row.Name }}</td>
        <td>{{ row.Index }}</td>
      </tr>
    </tbody></table>
  </div>
</div></template>

<script>
export default {
  async asyncData ({$content}) {
    return {
      data: await $content('pres').fetch()
    };
  }
};
</script>

The browser should refresh to show the contents of the spreadsheet. If it does not, click Refresh manually or open a new browser window.

Nuxt Demo end of step 5

To verify that live reload works, open pres.xlsx from the content folder with Excel or another spreadsheet editor.

Set cell A7 to "SheetJS Dev" and set B7 to 47. Save the spreadsheet.

Adding a new line to pres.xlsx

The server terminal window should show a line like:

ℹ Updated ./content/pres.xlsx                                       @nuxt/content 05:43:37

The page should automatically refresh with the new content:

Nuxt Demo end of step 6

Stop the server (press CTRL+C in the terminal window).
Build the static site:

npm run generate

This will create a static site in the dist folder, which can be served with:

npx http-server dist

Accessing the page http://localhost:8080 will show the page contents. Verifying the static nature is trivial: make another change in Excel and save. The page will not change.

Nuxt Content v2

Nuxt Content v2 is designed to work with NuxtJS v3 and VueJS v3.

The following diagram depicts the workbook waltz:

Installation

The SheetJS NodeJS Module can be safely imported from nuxt.config.js or transformer or module scripts. As long as the SheetJS modules are not imported in the various .vue pages, the library will not be added to the final page bundle!

Custom Transformer

Nuxt Content v2 supports custom transformers for controlling data. Although the library hard-codes UTF-8 interpretations, the _id field currently uses the pattern content: followed by the filename (if files are placed in the content folder directly). This enables a transformer to re-read the file.

For example, if the file pres.xlsx is stored in the content folder, NuxtJS Content will use ID "content:pres.xlsx". "./content/" + _id.slice(8) will be the original path "./content/pres.xlsx".

The NodeJS resolve⁵ method will return a file path. readFileSync⁶ will read the file and return a NodeJS Buffer. That Buffer object can be parsed with the SheetJS read⁷ method. The sheet_to_json⁸ utility function can generate arrays of row objects for use in NuxtJS pages.

sheetformer.ts (Transformer)
// @ts-ignore
import { defineTransformer } from "@nuxt/content/transformers/utils";
import { read, utils } from "xlsx";
import { readFileSync } from "node:fs";
import { resolve } from 'node:path';

export default defineTransformer({
  name: 'sheetformer',
  /* list of file extensions */
  extensions: ['.xlsx'],
  parse (_id: string, rawContent: string) {
    /* read the underlying file */
    const buf = readFileSync(resolve("./content/" + _id.slice(8)));
    /* parse */
    const wb = read(buf);
    /* generate JS objects for each worksheet */
    const body = wb.SheetNames.map(name => ({
      name: name,
      data: utils.sheet_to_json(wb.Sheets[name])
    }));
    /* The final result must have the `_id` key and must store data in `body` */
    return { _id, body };
  }
});

The data object returned by the transformer must have the original _id key. The data is stored in the body property of the final object.

Custom Modules

NuxtJS modules are the main mechanism for adding transformers to the pipeline.

Module Details (click to show)

Due to the structure of the NuxtJS system, modules must be defined in separate script files. The module script is expected to export a module configured with defineNuxtModule. The setup method is expected to do the following:

Register itself with the "Nitro" subsystem
Add the transformer to Nuxt Content in the content:context hook

sheetmodule.ts (Module)
import { resolve } from 'path'
import { defineNuxtModule } from '@nuxt/kit'

export default defineNuxtModule({
  /* module setup method */
  setup (_options, nuxt) {
    /* register with the nitro subsystem */
    nuxt.options.nitro.externals = nuxt.options.nitro.externals || {};
    nuxt.options.nitro.externals.inline = nuxt.options.nitro.externals.inline || [];
    nuxt.options.nitro.externals.inline.push(resolve('./sheetmodule'));

    /* add transformer in the content:context hook */
    // @ts-ignore
    nuxt.hook('content:context', (contentContext) => {
      contentContext.transformers.push(resolve('./sheetformer.ts'));
    });
  }
});

The module must be loaded in nuxt.config.ts and added to the modules array:

nuxt.config.ts
import SheetJSModule from './sheetmodule'

export default defineNuxtConfig({
  // @ts-ignore
  telemetry: false,
  modules: [
    SheetJSModule,
    /* it is recommended to load the custom modules before @nuxt/content */
    '@nuxt/content'
  ],
  content: {}
});

Rendering Data

Pages can pull data using useAsyncData in the page setup:

Script section of .vue VueJS page
<script setup>
const key = "pres"; // matches pres.xlsx
const { data } = await useAsyncData('x', ()=>queryContent(`/${key}`).findOne());
</script>

Pages should use ContentRenderer to reference the data. The data variable from the script setup will be shaped like the return value from the transformer. data.body is an array of objects that holds the worksheet name and data.

Template section of .vue VueJS page
<template>
  <ContentRenderer :value="data">
    <!-- data.body is the array defined in the transformer -->
    <div v-for="item in data.body" v-bind:key="item.name">
      <!-- each item has a "name" string for worksheet name -->
      <h2>{{ item.name }}</h2>
      <!-- each item has a "body" array of data rows -->
      <table><thead><tr><th>Name</th><th>Index</th></tr></thead><tbody>
        <tr v-for="row in item.data" v-bind:key="row.Index">
          <!-- Assuming the sheet uses the columns "Name" and "Index" -->
          <td>{{ row.Name }}</td>
          <td>{{ row.Index }}</td>
        </tr>
      </tbody></table>
    </div>
  </ContentRenderer>
</template>

Nuxt Content 2 Demo

For some older versions, parts of the Nuxt dependency tree did not support NodeJS version 20. If the yarn install step fails with a message like

error @nuxt/[email protected]: The engine "node" is incompatible with this module.

The recommended solution is to switch to Node 18.

Create a stock app and install dependencies:

npx -y nuxi init -t content sheetjs-nc2
cd sheetjs-nc2
npx -y yarn install
npx -y yarn add --dev @types/node

Install the SheetJS library and start the server:

npx -y yarn add https://cdn.sheetjs.com/xlsx-0.20.2/xlsx-0.20.2.tgz
npx -y yarn dev

When the build finishes, the terminal will display a URL like:

  > Local:    http://localhost:3000/

The server is listening on that URL. Open the link in a web browser.

Download https://sheetjs.com/pres.xlsx and move to the content folder.

curl -L -o content/pres.xlsx https://sheetjs.com/pres.xlsx

Create the transformer. Two files must be saved at the root of the project:

sheetformer.ts (raw transformer module)
sheetmodule.ts (Nuxt configuration module)

curl -O https://docs.sheetjs.com/nuxt/3/sheetformer.ts
curl -O https://docs.sheetjs.com/nuxt/3/sheetmodule.ts

After creating the source files, the module must be added to nuxt.config.ts:

nuxt.config.ts (add highlighted lines)
import SheetJSModule from './sheetmodule'

export default defineNuxtConfig({
  // @ts-ignore
  telemetry: false,
  devtools: { enabled: true },
  modules: [
    SheetJSModule,
    '@nuxt/content'
  ],
  content: {}
});

Restart the dev server by exiting the process (Control+C) and running:

npx -y nuxi clean
npx -y nuxi cleanup
npx -y nuxi typecheck
npx -y yarn run dev

Loading http://localhost:3000/pres should show some JSON data:

{
  // ...
  "data": {
    "_path": "/pres",
    // ...
    "_id": "content:pres.xlsx",
    "body": [
      {
        "name": "Sheet1", // <-- sheet name
        "data": [ // <-- array of data objects
          {
            "Name": "Bill Clinton",
            "Index": 42
          },

Download pres.vue and save to pages:

curl -o pages/pres.vue https://docs.sheetjs.com/nuxt/3/pres.vue

Restart the dev server by exiting the process (Control+C) and running:

npx -y nuxi clean
npx -y nuxi cleanup
npx -y yarn run dev

The browser should now display an HTML table.

To verify that hot loading works, open pres.xlsx from the content folder with Excel or another spreadsheet editor.

Set cell A7 to "SheetJS Dev" and set B7 to 47. Save the spreadsheet.

The page should automatically refresh with the new content.

Stop the server (press CTRL+C in the terminal window).
Build the static site:

npx -y yarn run generate

This will create a static site in .output/public, which can be served with:

npx -y http-server .output/public

Accessing http://localhost:8080/pres will show the page contents. Verifying the static nature is trivial: make another change in Excel and save. The page will not change.

See readFile in "Reading Files" ↩
See sheet_to_json in "Utilities" ↩
See extendParser in the NuxtJS documentation. ↩
See "Array of Objects" in the VueJS demo ↩
See resolve in the NodeJS node:path documentation ↩
See readFileSync in the NodeJS node:fs documentation ↩
See read in "Reading Files" ↩
See sheet_to_json in "Utilities" ↩

Nuxt Content v1​

Installation​

Custom Parser​

Configuration​

Template Use​

Nuxt Content Demo​

Nuxt Content v2​

Installation​

Custom Transformer​

Custom Modules​

Rendering Data​

Nuxt Content 2 Demo​

Footnotes​

Nuxt Content v1

Installation

Custom Parser

Configuration

Template Use

Nuxt Content Demo

Nuxt Content v2

Installation

Custom Transformer

Custom Modules

Rendering Data

Nuxt Content 2 Demo

Footnotes