2024.4.121 • Public • Published

NPM Donate for Corifeus / P3X Contact Corifeus / P3X Corifeus @ Facebook Uptime Robot ratio (30 days)

📈 Convert JSON to Excel XLSX with offloading the constructing the data using a worker thread v2024.4.121

Bugs are evident™ - MATRIX️

NodeJS LTS is supported

Built on NodeJs version



Utility to convert json to an excel file, based on Node-Excel-Export using a worker thread by not blocking the NodeJs event loop using async functions and options.

This is a totally fork of the json2xls, but the XLSX constructing can be CPU intensive so we are offloading the XLSX constructing using a worker thread.

Of course, when using a worker thread, the execution is about 20-25ms longer, than when we are in the event loop, so the worker thread is valid when we are generating a big dataset.


npm install p3x-json2xls-worker-thread


Use to save as file:

const json2xls = require('p3x-json2xls-worker-thread')
const fs = require('fs').promises

const json = {
    foo: 'bar',
    qux: 'moo',
    poo: 123,
    stux: new Date()
const executAsync = async() => {    
    try {
        let nodeExcelOptions = undefined
        The following options are supported:       
            - style: a styles xml file, see <https://github.com/functionscope/Node-Excel-Export>
            - fields: either an array or map containing field configuration:
                - array: a list of names of fields to be exported, in that order
                - object: a map of names of fields to be exported and the types of those fields. Supported types are 'number','string','bool'
        if (ifSomeConditionIsTrue) {
            nodeExcelOptions = {
                fields: ['poo']
        const options = {
            output: 'binary' /* default */ || 'base64',
            nodeExcel: nodeExcelOptions
        const xlsBinary = await json2xls(json, options)
        await fs.writeFile('data.xlsx', xlsBinary, 'binary');
    } catch(e) {
        // handle error

Or use as express middleware. It adds a convenience xls method to the response object to immediately output an excel as download.

const json2xls = require('p3x-json2xls-worker-thread')

const jsonArr = [{
    foo: 'bar',
    qux: 'moo',
    poo: 123,
    stux: new Date()
    foo: 'bar',
    qux: 'moo',
    poo: 345,
    stux: new Date()


app.get('/',function(req, res) {
    res.xls('data.xlsx', jsonArr);

It is possible to block the event loop by using the sync function eg.:

const json2xls = require('p3x-json2xls-worker-thread')

const json = {
    foo: 'bar',
    qux: 'moo',
    poo: 123,
    stux: new Date()

const xlsBinary = json2xls.sync(json, {
    output: 'base64' // can be binary as well, just sugar...


Support Our Open-Source Project ❤️

If you appreciate our work, consider starring this repository or making a donation to support server maintenance and ongoing development. Your support means the world to us—thank you!

Server Availability

Our server may occasionally be down, but please be patient. Typically, it will be back online within 15-30 minutes. We appreciate your understanding.

About My Domains

All my domains, including patrikx3.com and corifeus.com, are developed in my spare time. While you may encounter minor errors, the sites are generally stable and fully functional.

Versioning Policy

Version Structure: We follow a Major.Minor.Patch versioning scheme:

  • Major: Corresponds to the current year.
  • Minor: Set as 4 for releases from January to June, and 10 for July to December.
  • Patch: Incremental, updated with each build.

Important Changes: Any breaking changes are prominently noted in the readme to keep you informed.

P3X-JSON2XLS-WORKER-THREAD Build v2024.4.121

NPM Donate for Corifeus / P3X Contact Corifeus / P3X Like Corifeus @ Facebook

Package Sidebar


npm i p3x-json2xls-worker-thread

Weekly Downloads






Unpacked Size

13.5 kB

Total Files


Last publish


  • patrikx3