If you mean the standard browser implementation, Crypto.getRandomValues()² may be what you're looking for. Note that the browser implementation of this is only a recommendation, so YMMV:
> To guarantee enough performance, implementations are not using a truly random number generator, but they are using a pseudo-random number generator seeded with a value with enough entropy. The pseudo-random number generator algorithm (PRNG) may vary across user agents, but is suitable for cryptographic purposes. Implementations are required to use a seed with enough entropy, like a system-level entropy source.
> [...]
> There is no minimum degree of entropy mandated by the Web Cryptography specification. User agents are instead urged to provide the best entropy they can when generating random numbers, using a well-defined, efficient pseudorandom number generator built into the user agent itself, but seeded with values taken from an external source of pseudorandom numbers, such as a platform-specific random number function, the Unix /dev/urandom device, or other source of random or pseudorandom data.
¹ https://nodejs.org/api/crypto.html#crypto_crypto_randombytes...
² https://developer.mozilla.org/en-US/docs/Web/API/Crypto/getR...
... neither crypto.getRandomBytes() nor Crypto.getRandomValues() are SEEDABLE. There is no argument I could pass in that would produce the same random sequence for the same seed-value.
A reproducible random sequence would be useful in many situations I believe. I understand such a thing is not too difficult to program but it may be difficult to get verifiably good quality randomness out of your own implementation.