What is JavaScript BigDecimal? How To Get Big Numbers

This article explores two key approaches to working with BigDecimal big numbers in JavaScript: using the built-in BigInt feature for large integers and leveraging the “decimal.js” library for precise decimal arithmetic.

What is JavaScript BigDecimal?

In JavaScript, there is no native “BigDecimal” data type like you might find in some other programming languages, such as Java. JavaScript primarily uses the “number” data type to represent both integer and floating-point numbers.

This means that JavaScript’s built-in number type has limitations when it comes to precision, especially when working with very large or very small numbers.

If you need precise decimal arithmetic in JavaScript, you often have to rely on third-party libraries or implement your own custom solutions.

One popular library for arbitrary-precision decimal arithmetic in JavaScript is “decimal.js.” This library allows you to perform mathematical operations with a high degree of precision.

What is an example of a BigDecimal?

Here’s an example of how you might use the “decimal.js” library to work with BigDecimal-like numbers in JavaScript:

First, include the library in your project:

<script src="decimal.js"></script>

Then, you can use it in your JavaScript code:

// Import the Decimal class from the library
const Decimal = require('decimal.js');

// Create BigDecimal-like numbers
const num1 = new Decimal('10.12345678901234567890');
const num2 = new Decimal('5.67890123456789012345');

// Perform arithmetic operations
const sum = num1.plus(num2);
const product = num1.times(num2);

console.log('Sum:', sum.toString());
console.log('Product:', product.toString());

This way, you can work with arbitrary precision decimal numbers in JavaScript using the “decimal.js” library, which provides functionality similar to BigDecimal in other programming languages.

How to get big numbers in JavaScript?

In JavaScript, you can represent and work with big numbers (numbers with arbitrary precision) using libraries like “BigInt” and “decimal.js.” These libraries allow you to perform mathematical operations with large and precise numbers.

Here’s how to use both of these libraries to work with big numbers:

  1. Using BigInt: BigInt is a built-in JavaScript feature that allows you to work with arbitrarily large integers.
   // Creating BigInt values
   const bigInt1 = BigInt("1234567890123456789012345678901234567890");
   const bigInt2 = BigInt(9876543210987654321098765432109876543210);

   // Performing arithmetic operations
   const sum = bigInt1 + bigInt2;
   const product = bigInt1 * bigInt2;

   console.log("Sum:", sum.toString());
   console.log("Product:", product.toString());

BigInts are integers, so they are best suited for operations that involve whole numbers.

  1. Using decimal.js: If you need to work with big numbers that have decimal points and require high precision, you can use the “decimal.js” library as mentioned in the previous answer.

Here’s a quick example:

   // Import the Decimal class from the library
   const Decimal = require('decimal.js');

   // Create Decimal objects
   const num1 = new Decimal('1234567890.123456789012345678901234567890');
   const num2 = new Decimal('9876543210.987654321098765432109876543210');

   // Perform arithmetic operations
   const sum = num1.plus(num2);
   const product = num1.times(num2);

   console.log('Sum:', sum.toString());
   console.log('Product:', product.toString());

“decimal.js” provides arbitrary-precision decimal arithmetic, which is useful when you need to work with numbers that have both integer and fractional parts and require precise calculations.

Choose the library that best suits your needs based on whether you’re working with integers (BigInt) or decimal numbers with high precision (“decimal.js”).

Conclusion

When you encounter scenarios in JavaScript that demand the manipulation of big numbers, you have options to address the challenge.

For dealing with large integers, the native BigInt feature is a powerful tool, allowing you to work with arbitrarily large whole numbers efficiently.

On the other hand, if your requirements involve both integer and fractional parts with high precision, “decimal.js” is a valuable library that brings the flexibility of BigDecimal-like arithmetic to JavaScript.

By understanding and using these tools, you can confidently tackle numerical challenges in your JavaScript applications, no matter how big or precise the numbers may be.

Frequently Asked Questions

Is JavaScript still worth learning in 2026?
Yes. JavaScript runs on 98% of websites for the front-end, dominates the back-end via Node.js, powers mobile apps through React Native, builds desktop tools through Electron, and is the scripting layer for most AI tooling (LangChain.js, OpenAI SDK, Vercel AI). Whether you target web, mobile, AI, or full-stack capstones, JavaScript is the broadest single language you can learn.
What is the difference between var, let, and const?
var is function-scoped, hoisted to the top of its scope, and can be redeclared, which leads to bugs in modern code. let is block-scoped (only visible inside the nearest {}) and can be reassigned. const is block-scoped and cannot be reassigned, although object contents can still mutate. Default to const for everything, switch to let only when you actually need to reassign, and avoid var in any code written after 2017.
Which JavaScript version should I target in 2026?
Target ES2020 (ES11) as the safe baseline because every modern browser and Node.js 14+ supports it fully. ES2022 adds useful features like top-level await, private class fields with the # prefix, and the .at() array method. If you are writing for older browsers (IE11 or older Android WebViews), transpile down with Babel or use a build tool like Vite, esbuild, or webpack.
What is the best free editor for JavaScript?
Visual Studio Code is the industry standard, free, with built-in IntelliSense, debugger, terminal, Git, and a huge extension marketplace (ESLint, Prettier, GitHub Copilot, Tailwind). Install the JavaScript and TypeScript Nightly extension for the latest language features. JetBrains WebStorm is more powerful and free for students with a verified .edu email. For quick scratchpad work, the Chrome DevTools Sources panel includes a workspace and breakpoint debugger.
How do I run JavaScript locally vs in the browser?
In the browser: open DevTools with F12 (or right-click then Inspect), go to the Console tab, type or paste your code, press Enter. For HTML pages, add a script tag pointing to your .js file. Locally with Node.js: download Node from nodejs.org (LTS version), then run node script.js in your terminal from the file folder. Use the same Node setup for backend capstones, API integrations, and scripts that do not need a browser.
What can I build with JavaScript for my BSIT capstone?
Common BSIT capstones in JavaScript: full-stack web apps using React or Vue on the front-end with Node.js and Express on the back-end (MongoDB or MySQL for the database), real-time chat or notification systems using Socket.io, single-page dashboards with Chart.js or D3.js, cross-platform mobile apps with React Native, AI-powered chatbots using OpenAI SDK and LangChain.js, and Chrome extensions for productivity tools. Add Tailwind CSS for the UI and Vercel or Netlify for free deployment.

Glay Eliver


Programmer & Technical Writer at PIES IT Solution

Glay Eliver is a programmer and writer at PIES IT Solution, author of over 600 tutorials at itsourcecode.com. Specializes in JavaScript tutorials, Microsoft Office how-tos (Excel, Word, PowerPoint), and Python error debugging covering ImportError, TypeError, AttributeError, ModuleNotFoundError, and JavaScript ReferenceError. Authored several of the site’s highest-traffic Excel and MS Office reference articles.

Expertise: JavaScript · MS Excel · MS Word · MS PowerPoint · Python · Python ImportError · Python TypeError · Python AttributeError · ModuleNotFoundError · JavaScript ReferenceError · Pygame
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