That looks like I was responding to Mark Hahn's commnet about sorting; I wasn't.
Of course it's fine to put the date on there *also*, but my point is
merely that (Date.now() + Math.random()) is not sufficiently random to
call it a uuid.
On Mon, Aug 6, 2012 at 6:09 PM, Isaac Schlueter <i...@izs.me> wrote:
> Math.random() is not cryptographically secure entropy, and Date.now()
> is extremely guessable. If you are worried about someone *wanting* to
> cause collisions, then that's not so great.
>
> If you don't care about the IETF, and you are writing your program in
> Node, then the simplest approach is something like:
>
> var uuid = crypto.randomBytes(24).toString('base64')
>
> To do it asynchronously (since the crypto ops are a little slow):
>
> crypto.randomBytes(24, function (er, bytes) {
> var uuid = bytes.toString('base64')
> })
>
> Make the number bigger or smaller to adjust the amount of entropy.
>
> Note that IETF uuids are "only" 16 bytes of entropy, so if you do want
> IETF-style uuids, you can do this:
>
> var uuid = crypto.randomBytes(16).toString('hex')
> var ietfStyle = uuid.replace(/^(.{8})(.{4})(.{4})(.{4})(.{12})$/,
> '$1-$2-$3-$4-$5')
>
> I'm going to be moving npm to just use base64 random bytes for salt
> eventually, just never got around to it.
>
>
> On Mon, Aug 6, 2012 at 4:02 PM, Mark Hahn <m...@hahnca.com> wrote:
>> The advantage of starting off with the time is that the UUIDs sort by order
>> generated which is useful for DB ids. Coding a time into base 36 is a bit
>> dangerous though as it may not sort right at some time in the future. That
>> time may be centuries from now, not sure. Sorting by hex is known to be far
>> in the future.
>>
>>
>> On Mon, Aug 6, 2012 at 3:56 PM, Mark Hahn <m...@hahnca.com> wrote:
>>>
>>> FWIW, here is the code to exactly match couchdb.
>>>
>>> UUID = -> '0' + (new Date().getTime() * 1e3).toString(16) +
>>> Math.floor(Math.random() * 1e18).toString(16)
>>>
>>>
>>> On Mon, Aug 6, 2012 at 3:43 PM, Rick Waldron <waldron.r...@gmail.com>
>>> wrote:
>>>>
>>>> On Mon, Aug 6, 2012 at 6:28 PM, Mark Hahn <m...@hahnca.com> wrote:
>>>>>
>>>>> That isn't a hack. It is almost a copy of what couchdb offers. I use
>>>>> it all the time.
>>>>
>>>>
>>>> One is an IETF (RFC) and the other isn't.
>>>>
>>>> http://www.ietf.org/rfc/rfc4122.txt
>>>>
>>>>>
>>>>>
>>>>> On Mon, Aug 6, 2012 at 2:17 PM, Ted Young <t...@radicaldesigns.org>
>>>>> wrote:
>>>>>>
>>>>>> Thanks for the feedback, glad to know I found the defacto solution.
>>>>>> Tim, that's funny, your hack is more or less what I started with, but I
>>>>>> became suspicious that it was too easy somehow. Maybe I'll switch back
>>>>>> to
>>>>>> that if file-size/performance becomes an issue (which it won't).
>>>>>>
>>>>>> Ted
>>>>>>
>>>>>> On Aug 6, 2012, at 8:27 PM, Tim Caswell <t...@creationix.com> wrote:
>>>>>>
>>>>>> Depending on how strict your requirements are, I often just use:
>>>>>>
>>>>>> Date.now.toString(36) + "-" + (Math.random() *
>>>>>> 0x10000000).toString(36)
>>>>>>
>>>>>> Date.now is unique every ms and Math.random has a keyspace of 2^32, so
>>>>>> collisions are statistically impossible in most practical
>>>>>> applications.
>>>>>>
>>>>>>
>>>>>> On Mon, Aug 6, 2012 at 1:01 PM, Rick Waldron <waldron.r...@gmail.com>
>>>>>> wrote:
>>>>>>
>>>>>>
>>>>>> On Monday, August 6, 2012 at 1:38 PM, Martin Cooper wrote:
>>>>>>
>>>>>> On Mon, Aug 6, 2012 at 10:28 AM, Ted Young <t...@radicaldesigns.org>
>>>>>> wrote:
>>>>>>
>>>>>> Hey y'all,
>>>>>>
>>>>>> So, I have a need for global unique id's. Googling about, I've found
>>>>>> the
>>>>>> following implementations that seem decent:
>>>>>>
>>>>>> https://github.com/broofa/node-uuid
>>>>>>
>>>>>>
>>>>>> FWIW, this is the package that npm uses.
>>>>>>
>>>>>> +1
>>>>>>
>>>>>> I've been using Robert Keiffer's impl in projects since before it was
>>>>>> even
>>>>>> on npm—I consider it a "go to"
>>>>>>
>>>>>> Rick
>>>>>>
>>>>>>
>>>>>> --
>>>>>> Martin Cooper
>>>>>>
>>>>>>
>>>>>> https://gist.github.com/1308368
>>>>>>
>>>>>> Not really sure why I would pick one over the other (besides file
>>>>>> size), or
>>>>>> if there are any js-specific issues I should be aware of. Any advice?
>>>>>>
>>>>>> Cheers,
>>>>>>
>>>>>> Ted
>>>>>>
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