BigInt() constructor

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since September 2020.

The BigInt() function returns primitive values of type BigInt.

Syntax

BigInt(value)

Note: BigInt() can only be called without new. Attempting to construct it with new throws a TypeError.

Parameters

value: The value to be converted to a BigInt value. It may be a string, an integer, a boolean, or another BigInt.

A BigInt value. Number values must be integers and are converted to BigInts. The boolean value true becomes 1n, and false becomes 0n. Strings are parsed as if they are source text for integer literals, which means they can have leading and trailing whitespaces and can be prefixed with 0b, 0o, or 0x.

Exceptions

RangeError

Thrown if the parameter is a non-integral number.

TypeError

Thrown in one of the following cases:

The parameter cannot be converted to a primitive.
After conversion to a primitive, the result is undefined, null, symbol.

SyntaxError

Thrown if the parameter is a string that cannot be parsed as a BigInt.

Examples

Using BigInt() to convert a number to a BigInt

BigInt() is the only case where a number can be converted to a BigInt without throwing, because it's very explicit. However, only integers are allowed.

BigInt(123); // 123n
BigInt(123.3); // RangeError: The number 123.3 cannot be converted to a BigInt because it is not an integer

Using string values

BigInt("123"); // 123n
BigInt("0b10101"); // 21n, which is 10101 in binary
BigInt("0o123"); // 83n, which is 123 in octal
BigInt("0x123"); // 291n, which is 123 in hexadecimal
BigInt("  123  "); // 123n, leading and trailing whitespaces are allowed

Specifications

Specification
ECMAScript® 2026 Language Specification # sec-bigint-constructor