JavaScript BigInt : Object

primitive

An arbitrarily large integer value. Allows storing integers larger than what Number allows. Use Number(bigInt) to convert a BigInt to a Number.

ECMAScript 2020 Spec

BigInt(int : Number) : BigInt

Creates a BigInt for the specified number. int should be between Number.MIN_SAFE_INTEGER and Number.MAX_SAFE_INTEGER.

Example:

// The following are equivalent
const w = BigInt(15);
const x = 15n; // Decimal
const y = 0xFn; // Hex
const z = 0b1111n; // Binary

console.log(w + x);

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Results:

Spec

BigInt(int : String) : BigInt

Converts the specified string to a BigInt. Allows constructing BigInts larger than Numbers.

Example:

// The following are equivalent
const x = BigInt('15');
const y = BigInt('0xF'); // Hex
const z = BigInt('0b1111'); // Binary

// The String constructor allows creating BigInts larger than Number allows
const a = BigInt('9999999999999999');
const b = BigInt(9999999999999999); // Exceeds Number.MAX_SAFE_INTEGER
const c = 9999999999999999n;
console.log(a);
console.log(b);
console.log(c);

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Results:

Spec

Instance Methods

asIntN(n : Number, bigInt : BigInt) : BigInt

Truncates bigInt to an n-bit signed integer.

Example:

console.log(BigInt.asIntN(16, 0x0001n));
console.log(BigInt.asIntN(16, 0x7FFFn));
console.log(BigInt.asIntN(16, 0x8000n));
console.log(BigInt.asIntN(16, 0xFFFFn));
console.log(BigInt.asIntN(16, 0x10000n));

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Results:

Spec

asUintN(n : Number, bigInt : BigInt) : BigInt

Truncates bigInt to an n-bit unsigned integer.

Example:

console.log(BigInt.asUintN(16, 0x0001n));
console.log(BigInt.asUintN(16, 0x7FFFn));
console.log(BigInt.asUintN(16, 0x8000n));
console.log(BigInt.asUintN(16, 0xFFFFn));
console.log(BigInt.asUintN(16, 0x10000n));

Run

Results:

Spec

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