BigInt
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.
BigInt
values represent numeric values which are too large to be represented by the number
primitive.
Description
A BigInt value, also sometimes just called a BigInt, is a bigint
primitive, created by appending n
to the end of an integer literal, or by calling the BigInt()
function (without the new
operator) and giving it an integer value or string value.
const previouslyMaxSafeInteger = 9007199254740991n;
const alsoHuge = BigInt(9007199254740991);
// 9007199254740991n
const hugeString = BigInt("9007199254740991");
// 9007199254740991n
const hugeHex = BigInt("0x1fffffffffffff");
// 9007199254740991n
const hugeOctal = BigInt("0o377777777777777777");
// 9007199254740991n
const hugeBin = BigInt(
"0b11111111111111111111111111111111111111111111111111111",
);
// 9007199254740991n
BigInt values are similar to Number values in some ways, but also differ in a few key matters: A BigInt value cannot be used with methods in the builtin Math
object and cannot be mixed with a Number value in operations; they must be coerced to the same type. Be careful coercing values back and forth, however, as the precision of a BigInt value may be lost when it is coerced to a Number value.
Type information
When tested against typeof
, a BigInt value (bigint
primitive) will give "bigint"
:
typeof 1n === "bigint"; // true
typeof BigInt("1") === "bigint"; // true
A BigInt value can also be wrapped in an Object
:
typeof Object(1n) === "object"; // true
Operators
Most operators support BigInts, however most do not permit operands to be of mixed types — both operands must be BigInt or neither:
 Arithmetic operators:
+
,
,*
,/
,%
,**
 Bitwise operators:
>>
,<<
,&
,
,^
,~
 Unary negation (

)  Increment/decrement:
++
,
The booleanreturning operators allow mixing numbers and BigInts as operands:
 Relational operators and equality operators:
>
,<
,>=
,<=
,==
,!=
,===
,!==
 Logical operators only rely on the truthiness of operands
A couple of operators do not support BigInt at all:
 Unary plus (
+
) cannot be supported due to conflicting usage in asm.js, so it has been left out in order to not break asm.js.  Unsigned right shift (
>>>
) is the only bitwise operator that's unsupported, as every BigInt value is signed.
Special cases:
 Addition (
+
) involving a string and a BigInt returns a string.  Division (
/
) truncates fractional components towards zero, since BigInt is unable to represent fractional quantities.
const previousMaxSafe = BigInt(Number.MAX_SAFE_INTEGER); // 9007199254740991n
const maxPlusOne = previousMaxSafe + 1n; // 9007199254740992n
const theFuture = previousMaxSafe + 2n; // 9007199254740993n, this works now!
const prod = previousMaxSafe * 2n; // 18014398509481982n
const diff = prod  10n; // 18014398509481972n
const mod = prod % 10n; // 2n
const bigN = 2n ** 54n; // 18014398509481984n
bigN * 1n; // 18014398509481984n
const expected = 4n / 2n; // 2n
const truncated = 5n / 2n; // 2n, not 2.5n
Comparisons
A BigInt value is not strictly equal to a Number value, but it is loosely so:
0n === 0; // false
0n == 0; // true
A Number value and a BigInt value may be compared as usual:
1n < 2; // true
2n > 1; // true
2 > 2; // false
2n > 2; // false
2n >= 2; // true
BigInt values and Number values may be mixed in arrays and sorted:
const mixed = [4n, 6, 12n, 10, 4, 0, 0n];
// [4n, 6, 12n, 10, 4, 0, 0n]
mixed.sort(); // default sorting behavior
// [ 12n, 0, 0n, 10, 4n, 4, 6 ]
mixed.sort((a, b) => a  b);
// won't work since subtraction will not work with mixed types
// TypeError: can't convert BigInt value to Number value
// sort with an appropriate numeric comparator
mixed.sort((a, b) => (a < b ? 1 : a > b ? 1 : 0));
// [ 12n, 0, 0n, 4n, 4, 6, 10 ]
Note that comparisons with Object
wrapped BigInt values act as with other objects, only indicating equality when the same object instance is compared:
Object(0n) === 0n; // false
Object(0n) === Object(0n); // false
const o = Object(0n);
o === o; // true
Because coercing between Number values and BigInt values can lead to loss of precision, the following are recommended:
 Only use a BigInt value when values greater than 2^{53} are reasonably expected.
 Don't coerce between BigInt values and Number values.
Conditionals
A BigInt value follows the same conversion rules as Numbers when:
 it is converted to a
Boolean
: via theBoolean
function;  when used with logical operators

,&&
, and!
; or  within a conditional test like an
if
statement.
Namely, only 0n
is falsy; everything else is truthy.
if (0n) {
console.log("Hello from the if!");
} else {
console.log("Hello from the else!");
}
// "Hello from the else!"
0n  12n; // 12n
0n && 12n; // 0n
Boolean(0n); // false
Boolean(12n); // true
!12n; // false
!0n; // true
Cryptography
The operations supported on BigInt values are not constanttime and are thus open to timing attacks. JavaScript BigInts therefore could be dangerous for use in cryptography without mitigating factors. As a very generic example, an attacker could measure the time difference between 101n ** 65537n
and 17n ** 9999n
, and deduce the magnitude of secrets, such as private keys, based on the time elapsed. If you still have to use BigInts, take a look at the Timing attack FAQ for general advice regarding the issue.
Use within JSON
Using JSON.stringify()
with any BigInt value will raise a TypeError
, as BigInt values aren't serialized in JSON by default. However, JSON.stringify()
specifically leaves a backdoor for BigInt values: it would try to call the BigInt's toJSON()
method. (It doesn't do so for any other primitive values.) Therefore, you can implement your own toJSON()
method (which is one of the few cases where patching builtin objects is not explicitly discouraged):
BigInt.prototype.toJSON = function () {
return { $bigint: this.toString() };
};
Instead of throwing, JSON.stringify()
now produces a string like this:
console.log(JSON.stringify({ a: 1n }));
// {"a":{"$bigint":"1"}}
If you do not wish to patch BigInt.prototype
, you can use the replacer
parameter of JSON.stringify
to serialize BigInt values:
const replacer = (key, value) =>
typeof value === "bigint" ? { $bigint: value.toString() } : value;
const data = {
number: 1,
big: 18014398509481982n,
};
const stringified = JSON.stringify(data, replacer);
console.log(stringified);
// {"number":1,"big":{"$bigint":"18014398509481982"}}
You can then use the reviver
parameter of JSON.parse
to handle them:
const reviver = (key, value) =>
value !== null &&
typeof value === "object" &&
"$bigint" in value &&
typeof value.$bigint === "string"
? BigInt(value.$bigint)
: value;
const payload = '{"number":1,"big":{"$bigint":"18014398509481982"}}';
const parsed = JSON.parse(payload, reviver);
console.log(parsed);
// { number: 1, big: 18014398509481982n }
Note: While it's possible to make the replacer of JSON.stringify()
generic and properly serialize BigInt values for all objects as shown above, the reviver of JSON.parse()
has to be used with caution, because the serialization is irreversible: it's not possible to distinguish between an object that happens to have a property called $bigint
and an actual BigInt.
In addition, the example above creates an entire object during replacing and reviving, which may have performance or storage implications for larger objects containing many BigInts. If you know the shape of the payload, it may be better to just serialize them as strings and revive them based on the property key's name instead.
In fact, JSON allows number literals that are arbitrarily long; they just cannot be parsed to full precision in JavaScript. If you are communicating with another program in a language that supports longer integers (such as 64bit integers), and you want to transmit the BigInt as a JSON number instead of a JSON string, see Lossless number serialization.
BigInt coercion
Many builtin operations that expect BigInts first coerce their arguments to BigInts. The operation can be summarized as follows:
 BigInts are returned asis.
undefined
andnull
throw aTypeError
.true
turns into1n
;false
turns into0n
. Strings are converted by parsing them as if they contain an integer literal. Any parsing failure results in a
SyntaxError
. The syntax is a subset of string numeric literals, where decimal points or exponent indicators are not allowed.  Numbers throw a
TypeError
to prevent unintended implicit coercion causing loss of precision.  Symbols throw a
TypeError
.  Objects are first converted to a primitive by calling their
[Symbol.toPrimitive]()
(with"number"
as hint),valueOf()
, andtoString()
methods, in that order. The resulting primitive is then converted to a BigInt.
The best way to achieve nearly the same effect in JavaScript is through the BigInt()
function: BigInt(x)
uses the same algorithm to convert x
, except that Numbers don't throw a TypeError
, but are converted to BigInts if they are integers.
Note that builtin operations expecting BigInts often truncate the BigInt to a fixed width after coercion. This includes BigInt.asIntN()
, BigInt.asUintN()
, and methods of BigInt64Array
and BigUint64Array
.
Constructor
BigInt()

Returns primitive values of type BigInt. Throws an error when called with
new
.
Static methods
BigInt.asIntN()

Clamps a BigInt value to a signed integer value, and returns that value.
BigInt.asUintN()

Clamps a BigInt value to an unsigned integer value, and returns that value.
Instance properties
These properties are defined on BigInt.prototype
and shared by all BigInt
instances.
BigInt.prototype.constructor

The constructor function that created the instance object. For
BigInt
instances, the initial value is theBigInt
constructor. BigInt.prototype[Symbol.toStringTag]

The initial value of the
[Symbol.toStringTag]
property is the string"BigInt"
. This property is used inObject.prototype.toString()
. However, becauseBigInt
also has its owntoString()
method, this property is not used unless you callObject.prototype.toString.call()
with a BigInt asthisArg
.
Instance methods
BigInt.prototype.toLocaleString()

Returns a string with a languagesensitive representation of this BigInt value. Overrides the
Object.prototype.toLocaleString()
method. BigInt.prototype.toString()

Returns a string representing this BigInt value in the specified radix (base). Overrides the
Object.prototype.toString()
method. BigInt.prototype.valueOf()

Returns this BigInt value. Overrides the
Object.prototype.valueOf()
method.
Examples
Calculating Primes
// Returns true if the passed BigInt value is a prime number
function isPrime(p) {
for (let i = 2n; i * i <= p; i++) {
if (p % i === 0n) return false;
}
return true;
}
// Takes a BigInt value as an argument, returns nth prime number as a BigInt value
function nthPrime(nth) {
let maybePrime = 2n;
let prime = 0n;
while (nth >= 0n) {
if (isPrime(maybePrime)) {
nth;
prime = maybePrime;
}
maybePrime++;
}
return prime;
}
nthPrime(20n);
// 73n
Specifications
Specification 

ECMAScript Language Specification # secbigintobjects 
Browser compatibility
BCD tables only load in the browser