There already exists:

• JS_ToBigInt64()
• JS_NewBigUint64()
• JS_NewBigInt64()

Notably missing from this list is JS_ToBigUint64(), which means I have to cast my uint64_t * value to int64_t * when using the JS_ToBigInt64() function. Would be nice to not need to do the casting part, and makes sense to add it for API symmetry IMO.