BigInt

• Decimal: 123n.
• Binary: 0b1101n.
• Octal: 0o777n.
• Hexadecimal: 0xFFn.

/**
 * Takes a bigint as an argument and returns a bigint
 */
function nthPrime(nth) {
  if (typeof nth !== 'bigint')
    throw new TypeError('Not bigint')

  function isPrime(p) {
    for (let i = 2n; i < p; i++) {
      if (p % i === 0n)
        return false
    }

    return true
  }

  for (let i = 2n; ; i++) {
    if (isPrime(i)) {
      if (--nth === 0n)
        return i
    }
  }
}

assert.deepEqual(
  [1n, 2n, 3n, 4n, 5n].map(nth => nthPrime(nth)),
  [2n, 3n, 5n, 7n, 11n]
)

Bigint Conversion

x	BigInt(x)
undefined	Throws TypeError
null	Throws TypeError
boolean	false → 0n, true → 1n
number	123 → 123n
	Non-integer → throws RangeError
bigint	x
string	'123' → 123n
	Unparsable → throws SyntaxError
symbol	Throws TypeError
object	Configurable ([Symbol.toPrimitive]()/valueOf())

BigInt(undefined)
// TypeError: Cannot convert undefined to a BigInt
BigInt(null)
// TypeError: Cannot convert null to a BigInt
BigInt('abc')
// SyntaxError: Cannot convert abc to a BigInt
BigInt('123n')
// SyntaxError: Cannot convert 123n to a BigInt
BigInt('123')
// 123n
BigInt('0xFF')
// 255n
BigInt('0b1101')
// 13n
BigInt('0o777')
// 511n
BigInt(123.45)
// RangeError: The number 123.45 cannot be converted to a BigInt
BigInt(123)
// 123n
BigInt({
  valueOf() {
    return 123n
  },
})
// 123n

Convert To	Explicit Conversion	Coercion (Implicit Conversion)
boolean	Boolean(0n) → false	!0n → true
	Boolean(int) → true	!int → false
number	Number(7n) → 7	+int → TypeError
string	String(7n) → '7'	''+7n → '7'

Bigint Static Properties

• BigInt.asIntN(width, theInt): Casts theInt to width bits (signed).
• BigInt.asUintN(width, theInt): Casts theInt to width bits (unsigned).

const uint64a = BigInt.asUintN(64, 12345n)
const uint64b = BigInt.asUintN(64, 67890n)
const result = BigInt.asUintN(64, uint64a * uint64b)