This is a random nonce with a time-based component. It returns a unique 64 bit unsigned number string.
uniqueNonce() {
if(unique_nonce_entropy === null) {
const b = secureRandom.randomUint8Array(2)
unique_nonce_entropy = parseInt(b[0] << 8 | b[1], 10)
}
let long = Long.fromNumber(Date.now())
const entropy = ++unique_nonce_entropy % 0xFFFF
long = long.shiftLeft(16).or(Long.fromNumber(entropy));
return long.toString()
}
let unique_nonce_entropy = null
npm libraries used: long and secure-random