Generate random BigInt values in the browser of variable bit length

random.ts

/** Returns a random hex string of length chars. */
const randomHexString = (length: number): string => {
  return Array.from({ length }, () => Math.round(Math.random() * 0xf).toString(16)).join('')
}

/** Returns a random BigInt of n bits in length. */
export const randomBigIntN = (n: number): bigint => {
  return BigInt.asUintN(n, BigInt(`0x${randomHexString(Math.ceil(n / 4))}`))
}

/** Returns a uniformly distributed 32-bit unsigned integer. */
export const randomUint32 = (): number => Number(randomBigIntN(32))

/** Returns a uniformly distributed 64-bit unsigned integer. */
export const randomUint64 = (): bigint => randomBigIntN(64)