Will new Date().toJSON() always be unique in Javascript?

问题

The PouchDB Manual suggests using Date().toJSON() to generate a new id for each document. Do all javascript runtimes guarantee that Date().toJSON() will always be unique?

回答1:

The dates only have microsecond precision, so there's no guarantee they will be unique.

The snippet below will give you a number of duplicates in all but the slowest runtime environments:

for (let i = 0; i < 10; i++) {
  console.log(new Date().toJSON())
}

回答2:

In case of distributed system, We can also use this eventid module.

回答3:

I think the PouchDb guide mentioned using dates in that example so that documents would be in date/time order, not that this would ensure uniqueness. In the API you can see that if you do not specify an ID PouchDb will create a unique one for you.

来源：https://stackoverflow.com/questions/48415665/will-new-date-tojson-always-be-unique-in-javascript