Create Excel File In Javascript (Step-By-Step Example)

Welcome to a tutorial on how to create an Excel file in Javascript. Yes, you read that right. We are referring to “browser Javascript”, and not the server-side NodeJS. The dark days have passed and it is actually possible to generate Excel files using client-side Javascript – Read on for the examples!

ⓘ I have included a zip file with all the source code at the start of this tutorial, so you don’t have to copy-paste everything… Or if you just want to dive straight in.

 

 

TLDR – QUICK SLIDES

Fullscreen Mode – Click Here

 

TABLE OF CONTENTS

 

 

QUICK NOTES

If you spot a bug, feel free to comment below. I try to answer short questions too, but it is one person versus the entire world… If you need answers urgently, please check out my list of websites to get help with programming.

 

SCREENSHOT

 

EXAMPLE CODE DOWNLOAD

Click here to download all the example source code, I have released it under the MIT license, so feel free to build on top of it or use it in your own project.

 

 

 

EXAMPLE 1) GENERATE EXCEL FILE & FORCE DOWNLOAD

1A) THE HTML

<!-- (A) LOAD SHEETJS FROM CDN -->
<!-- https://sheetjs.com/ -->
<script src="https://cdnjs.cloudflare.com/ajax/libs/xlsx/0.18.5/xlsx.full.min.js"></script>
 
<!-- (B) CLICK TO GENERATE DEMO EXCEL -->
<button id="demo">Download Demo Excel</button>

<!-- (C) JAVASCRIPT -->
document.getElementById("demo").onclick = () => { ... };

Yep, that is pretty much everything we need to drive the example.

1. Load SheetJS from CDNJS, this library is required to create the Excel file. Will leave a link in the extras section below to their full documentation.
2. A demo button to start generating the Excel file.
3. Generate the Excel file when the button is clicked.

 

1B) DUMMY DATA

// (C1) DUMMY DATA
var data = [
  ["Joa Doe", "joa@doe.com"],
  ["Job Doe", "job@doe.com"],
  ["Joe Doe", "joe@doe.com"],
  ["Jon Doe", "jon@doe.com"],
  ["Joy Doe", "joy@doe.com"]
];

For the Javascript, we will first start by defining a nested array of dummy data. Don’t think it needs a lot of explanation, this will get “converted” into rows and columns in the Excel file.

 

 

1C) CREATE A NEW EXCEL OBJECT

// (C2) CREATE NEW EXCEL "FILE"
var workbook = XLSX.utils.book_new(),
    worksheet = XLSX.utils.aoa_to_sheet(data);
workbook.SheetNames.push("First");
workbook.Sheets["First"] = worksheet;

This should be pretty self-explanatory for the folks who already know Excel well, but for the sake of those who are new:

• A “workbook” is simply “the entire Excel file”.
• A “worksheet” is a table within a workbook.
• A workbook can contain multiple worksheets.

So what this section is doing:

• workbook = XLSX.utils.book_new() Creates a new Excel workbook.
• worksheet = XLSX.utils.aoa_to_sheet(data) Creates a new worksheet, using the dummy data array above.
• workbook.SheetNames.push("First") and workbook.Sheets["First"] = worksheet Attach the worksheet to the workbook.

 

1D) FORCE DOWNLOAD

// (C3) "FORCE DOWNLOAD" XLSX FILE
XLSX.writeFile(workbook, "demo.xlsx");

Horray, we now have an Excel object. All that’s left is to “force download” the Excel file, and allow the user to save it.

 

 

EXAMPLE 2) GENERATE EXCEL FILE & UPLOAD TO SERVER

2A) UPLOAD GENERATED EXCEL FILE

// (C3) TO BLOB
var xlsblob = new Blob(
  [new Uint8Array(XLSX.write(workbook, { bookType: "xlsx", type: "array" }))],
  {type:"application/octet-stream"}
);
 
// (C4) FORM DATA
var data = new FormData();
data.append("xls", xlsblob, "demo.xlsx");
 
// (C5) UPLOAD TO SERVER
fetch("2b-upload.php", { method: "POST", body: data })
.then(res => res.text())
.then(txt => console.log(txt));

This is an alternative if you want to upload the generated Excel file to the server instead.

• (C3) Instead of “forcing a download”, we turn the workbook into a blob (binary object).
• (C4) Attach the Excel blob as form data.
• (C5) Send the Excel blob to the server… Otherwise also known as “file upload”.

 

2B) SAVE THE UPLOADED EXCEL FILE

<?php
echo move_uploaded_file(
  $_FILES["xls"]["tmp_name"],
  __DIR__ . DIRECTORY_SEPARATOR . $_FILES["xls"]["name"]
) ? "OK" : "ERROR" ;

On the server side, we simply save the uploaded Excel file like a “normal file upload”. This is a simple “save uploaded file” snippet in PHP.

 

 

 

EFFICIENCY & PERFORMANCE

Just a quick note that we are holding an entire Excel file in the memory with this example… This will work great for small to medium Excel files, but the massive ones are going to run into performance issues and memory limits. You may want to implement some sort of restrictions on the maximum amount of data, or look at server-side alternatives with streaming.

 

COMPATIBILITY CHECKS

• Arrow Functions – CanIUse
• Array Buffer – CanIUse
• Uint8Array – Can I Use

This example will work on all modern “Grade A” browsers.

 

LINKS & REFERENCES

• SheetJS Documentation
• Export From MySQL Database To Excel In NodeJS – Code Boxx

 

INFOGRAPHICS CHEAT SHEET