JS BigInt

Regular JavaScript numbers are like a calculator display with a fixed number of digits; once a whole number gets big enough, it starts losing precision because it runs out of room. BigInt is a second numeric type that grows its digit tape as needed, letting you represent integers of essentially unlimited size, which regular numbers simply can't do accurately.

In this page:

What Is BigInt
Creating BigInt Values
BigInt Arithmetic
Mixing BigInt and Number
When to Use BigInt

Syntax

javascript

const bigNumber = 123n;
const bigNumber = BigInt(value);
bigA + bigB;

What Is BigInt

BigInt is a built-in numeric type for representing integers of arbitrary size, beyond the precision limits of the regular Number type.

You write a BigInt literal by appending the letter n to the end of an integer, such as 123n, which tells JavaScript to treat it as an exact, unlimited-size whole number rather than a floating-point Number.

उदाहरण: What Is BigInt

javascript

const big = 123n;
console.log(typeof big, big);

Creating BigInt Values

You can create a BigInt either with the n-suffixed literal syntax or by calling the BigInt() function on a number or numeric string.

The function form is useful when you need to convert a value that's already stored as a regular Number or string into a BigInt at runtime.

उदाहरण: Creating BigInt Values

javascript

// Declare the constant `a`, set to `123n`
// Declare the constant `a`, set to `123n`
const a = 123n;
// Declare the constant `b`, set to `BigInt(456)`
// Declare the constant `b`, set to `BigInt(456)`
const b = BigInt(456);
// Declare the constant `c`, set to `BigInt("789")`
// Declare the constant `c`, set to `BigInt("789")`
const c = BigInt("789");
// Print `a, b, c` to the console
// Print `a, b, c` to the console
console.log(a, b, c);

BigInt Arithmetic

BigInt supports the standard arithmetic operators +, -, *, and /, but division always truncates toward zero and discards any remainder, since BigInt has no concept of a fractional part.

This means 7n / 2n evaluates to 3n, not 3.5, which can surprise anyone expecting decimal division.

उदाहरण: BigInt Arithmetic

javascript

console.log(7n / 2n); // 3n, truncated toward zero, not 3.5

Mixing BigInt and Number

JavaScript deliberately throws a TypeError if you try to use arithmetic operators directly between a BigInt and a regular Number, since implicitly converting between the two could silently lose precision either way.

You must explicitly convert one side using BigInt() or Number() before combining them.

उदाहरण: Mixing BigInt and Number

javascript

try {
  console.log(5n + 5); // TypeError
} catch (e) {
  console.log(e.message);
}
console.log(5n + BigInt(5)); // works after explicit conversion

When to Use BigInt

BigInt is the right tool when a program needs exact integer arithmetic beyond about 9 quadrillion, such as cryptographic key calculations, high-precision timestamps, or unique identifiers imported from systems that use 64-bit integers.

For everyday counting and math, regular Numbers remain simpler and faster.

उदाहरण: When to Use BigInt

javascript

// Use BigInt for exact integers beyond ~9 quadrillion:
const id = 9007199254740993n;
console.log(id);
// Regular numbers are simpler for everyday counting:
const count = 5;
console.log(count);

Live Example

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JS BigInt

What Is BigInt

Creating BigInt Values

BigInt Arithmetic

Mixing BigInt and Number

When to Use BigInt

Chapter Quiz — Complete all 12 topics to unlock

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