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2020-12-21 13:33:45
UUIDs (Universally Unique IDentifier), also known as GUIDs (Globally Unique IDentifier), according to RFC 4122, are identifiers designed to provide certain uniqueness guarantees.
While it is possible to implement RFC-compliant UUIDs in a few lines of JavaScript code (e.g., see @broofa's answer, below) there are several common pitfalls:
- Invalid id format (UUIDs must be of the form "
xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx", where x is one of [0-9, a-f] M is one of [1-5], and N is [8, 9, a, or b] - Use of a low-quality source of randomness (such as
Math.random)
Thus, developers writing code for production environments are encouraged to use a rigorous, well-maintained implementation such as the uuid module.
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Actually, the RFC allows for UUIDs that are created from random numbers. You just have to twiddle a couple of bits to identify it as such. See section 4.4. Algorithms for Creating a UUID from Truly Random or Pseudo-Random Numbers: rfc-archive.org/getrfc.php?rfc=4122
This should not be the accepted answer. It does not actually answer the question - instead encouraging the import of 25,000 lines of code for something you can do with one line of code in any modern browser.
@AbhiBeckert the answer is from 2008 and for node.js projects it might be valid to choose a dependency more over project size
@Phil this is a "highly active question", which means it should have an excellent answer with a green tick. Unfortunately that's not the case. There is nothing wrong or incorrect with this answer (if there was, I'd edit the answer) - but another far better answer exists below and I think it should be at the top of the list. Also the question is specifically relating to javascript in a browser, not node.js.