/LICENSE.txt
forked from 140bytes/LICENSE.txt
Returns a random v4 UUID of the form xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx, where each x is replaced with a random hexadecimal digit from 0 to f, and y is replaced with a random hexadecimal digit from 8 to b.
There's also @LeverOne's approach using iteration, which is one byte shorter.
| function b( | |
| a // placeholder | |
| ){ | |
| return a // if the placeholder was passed, return | |
| ? ( // a random number from 0 to 15 | |
| a ^ // unless b is 8, | |
| Math.random() // in which case | |
| * 16 // a random number from | |
| >> a/4 // 8 to 11 | |
| ).toString(16) // in hexadecimal | |
| : ( // or otherwise a concatenated string: | |
| [1e7] + // 10000000 + | |
| -1e3 + // -1000 + | |
| -4e3 + // -4000 + | |
| -8e3 + // -80000000 + | |
| -1e11 // -100000000000, | |
| ).replace( // replacing | |
| /[018]/g, // zeroes, ones, and eights with | |
| b // random hex digits | |
| ) | |
| } |
| DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE | |
| Version 2, December 2004 | |
| Copyright (C) 2011 Jed Schmidt <http://jed.is> | |
| Everyone is permitted to copy and distribute verbatim or modified | |
| copies of this license document, and changing it is allowed as long | |
| as the name is changed. | |
| DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE | |
| TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION | |
| 0. You just DO WHAT THE FUCK YOU WANT TO. |
| { | |
| "name": "UUID", | |
| "description": "Generates random UUIDs", | |
| "keywords": [ | |
| "UUID", | |
| "ID", | |
| "random" | |
| ] | |
| } |
|
We can use coercion and exponential notation to get template string and save 7 bytes: |
|
subzey, you are a genius. fixing and annotating now. |
you also inspired me to cut 10 more bytes out:
function b(a){return a?(0|Math.random()*16).toString(16):(""+1e7+-1e3+-4e3+-8e3+-1e11).replace(/1|0/g,b)}|
you also inspired me to cut 10 more bytes out: function b(a){return a?(0|Math.random()*16).toString(16):(""+1e7+-1e3+-4e3+-8e3+-1e11).replace(/1|0/g,b)} |
(0|Math.random()*16).toString(16)can also be trimmed 4 bytes to
Math.random().toString(16)[2]if you don't care about IE... thoughts?
(0|Math.random()*16).toString(16)can also be trimmed 4 bytes to Math.random().toString(16)[2]if you don't care about IE... thoughts? |
|
@jed, Also, isn't setting name of function affects the outer scope? |
well, with the chance of Math.random returning a zero 1 in 2<<61, seems like the definition of an edge case. more likely that IE barfs on it.
also, we're allowing named functions because we assume that they'll be assigned externally.
|
well, with the chance of also, we're allowing named functions because we assume that they'll be assigned externally. |
|
@jed, thanks for your clarification about function names, I didn't know that |
|
@subzey, i hope you use this knowledge to bring us some awesome new stuff. |
""+1e7+-1e3+-4e3+-8e3+-1e11 --> [1e7]+-1e3+-4e3+-8e3+-1e11
it's а flaw of many of you.
|
""+1e7+-1e3+-4e3+-8e3+-1e11 --> [1e7]+-1e3+-4e3+-8e3+-1e11 |
|
@LeverOne, perfect! Thanks |
|
wow, that's crazy. good work @LeverOne. |
|
What about replacing |
the 4 is hardcoded according to the spec, and the 8 is a bit of a hack... technically it should be anything from 8 to b. so replacing those would make it less compliant.
|
the 4 is hardcoded according to the spec, and the 8 is a bit of a hack... technically it should be anything from 8 to b. so replacing those would make it less compliant. |
|
Ah I see, I missed that. |
i wonder if we finally have enough bytes to make it compliant, such that the 8 can be 8, 9, a, or b...
|
i wonder if we finally have enough bytes to make it compliant, such that the 8 can be 8, 9, a, or b... |
It is enough already :)
function c(a,b){return a?(~~b+0|Math.random()*16>>b/4).toString(16):([1e7]+-1e3+-4e3+-8e3+-1e11).replace(/1|0|(8)/g,c)}|
It is enough already :) function c(a,b){return a?(~~b+0|Math.random()*16>>b/4).toString(16):([1e7]+-1e3+-4e3+-8e3+-1e11).replace(/1|0|(8)/g,c)} |
Or this, shorter:
function c(a,b){return a?(b|Math.random()*16>>b/4).toString(16):([1e7]+-1e3+-4e3+-8e3+-1e11).replace(/1|0|(8)/g,c)}|
Or this, shorter: function c(a,b){return a?(b|Math.random()*16>>b/4).toString(16):([1e7]+-1e3+-4e3+-8e3+-1e11).replace(/1|0|(8)/g,c)} |
|
thanks again, @subzey. updated. |
Line 20 of annotated.js should be 'c', not 'b'.
BTW, you're all insane. I love it! :)
|
Line 20 of annotated.js should be 'c', not 'b'. BTW, you're all insane. I love it! :) |
good catch! for those not in the know, @broofa is a celebrity in the world of UUIDs: https://github.com/broofa/node-uuid
|
good catch! for those not in the know, @broofa is a celebrity in the world of UUIDs: https://github.com/broofa/node-uuid |
|
Maybe save 4 bytes...? |
|
what the... how on earth does this work? |
There are three possible values 0,1,8 for a.
For case 0: 0^Math.random()*16>>0/4, >>0/4 is actually >>0, just works as Math.floor.
The 0^ here does nothing.
For case 1: 1^Math.random()*16>>1/4, >>1/4 is still >>0.
Although 1^ here toggles the least significant bit, we can still use it to generate random numbers 0-15.
For case 8: 8^Math.random()*16>>8/4, >>8/4 turns out >>2.
The maximum number of Math.random()*16 in binary form is 1111, that means the range is 0000-1111.
By right shifting 2 bits, the maximum number of Math.random()*16>>2 is 0011, and the range, 0000-0011. What it does here is to generate random numbers 0-3.
Finally, because the most significant bit is always 0, 8^ is actually 8|, it is to ensure the range starts from 8. And now we get 8 + {0, 1, 2, 3}.
|
There are three possible values For case For case For case |
|
incredible work, @tsaniel! |
it's amazing how this gist has evolved, from
function(){return"00000000-0000-4000-8000-000000000000".replace(/0/g,function(){return(0|Math.random()*16).toString(16)})}to
function b(a){return a?(a^Math.random()*16>>a/4).toString(16):([1e7]+-1e3+-4e3+-8e3+-1e11).replace(/[018]/g,b)}while hitting all the greatest hits: recursion, coercion of a number into a string through an array (!), operator repurposing...
|
it's amazing how this gist has evolved, from function(){return"00000000-0000-4000-8000-000000000000".replace(/0/g,function(){return(0|Math.random()*16).toString(16)})}to function b(a){return a?(a^Math.random()*16>>a/4).toString(16):([1e7]+-1e3+-4e3+-8e3+-1e11).replace(/[018]/g,b)}while hitting all the greatest hits: recursion, coercion of a number into a string through an array (!), operator repurposing... |
I love those tricks, especially the string coercion with array, though i love bitwise tricks.
By the way, i am still thinking if we can shorten /[018]/...
|
I love those tricks, especially the string coercion with array, though i love bitwise tricks. |
|
@tsaniel - no way, the other way round would be |
|
@atk: That's true. I mean if we can do something to use |
...which would require that the 4 will be left alone and enlarge the equation probably more than the 3 letters we saved.
|
...which would require that the 4 will be left alone and enlarge the equation probably more than the 3 letters we saved. |
|
Maybe that's the end. |
|
I fear it is. |
|
Once again, excellent work, @tsaniel! Sorry for my late comment, my mobile browser doesn't work well with github |
|
Recursion & coercion vs. loop & math: https://gist.github.com/1308368 |
|
just when you thought it couldn't get any shorter, @LeverOne sheds a byte. good job! |
|
@LeverOne is my hero. |
|
damnit jed, i keep finding you everywhere. thanks for this! |
In Firefox you could use the single statement function body to shorten it a few bits still:
function b(a)a?(a^Math.random()*16>>a/4).toString(16):([1e7]+-1e3+-4e3+-8e3+-1e11).replace(/[018]/g,b)|
In Firefox you could use the single statement function body to shorten it a few bits still: function b(a)a?(a^Math.random()*16>>a/4).toString(16):([1e7]+-1e3+-4e3+-8e3+-1e11).replace(/[018]/g,b) |
Shorter yet (cheats, ES6, and works only in Firefox!!!), and less leaky:
function()([1e7]+-1e3+-4e3+-8e3+-1e11).replace(/[018]/g,a=>(a^Math.random()*16>>a/4).toString(16))|
Shorter yet (cheats, ES6, and works only in Firefox!!!), and less leaky: function()([1e7]+-1e3+-4e3+-8e3+-1e11).replace(/[018]/g,a=>(a^Math.random()*16>>a/4).toString(16)) |
Hah, since I already used ES6 and there are no variable assignments, might as well go all the way and avoid Firefox-only stuff:
()=>([1e7]+-1e3+-4e3+-8e3+-1e11).replace(/[018]/g,a=>(a^Math.random()*16>>a/4).toString(16))|
Hah, since I already used ES6 and there are no variable assignments, might as well go all the way and avoid Firefox-only stuff: ()=>([1e7]+-1e3+-4e3+-8e3+-1e11).replace(/[018]/g,a=>(a^Math.random()*16>>a/4).toString(16)) |
This is awesome!
Here's a benchmark vs node-uuid: http://jsperf.com/node-uuid-performance/11
|
This is awesome! Here's a benchmark vs node-uuid: http://jsperf.com/node-uuid-performance/11 |
|
I was so rooting for Crazy Gist to win that one :( |
Is this relatively safe to generate UUIDs simultaneously between many clients?
|
Is this relatively safe to generate UUIDs simultaneously between many clients? |
Make it secure at the cost of just a few bytes by replacing Math.random() * 16:
crypto.getRandomValues(new Uint8Array(1))[0] % 16
function b(
a // placeholder
){
return a // if the placeholder was passed, return
? ( // a random number from 0 to 15
a ^ // unless b is 8,
crypto.getRandomValues(new Uint8Array(1))[0] // in which case
% 16 // a random number from
>> a/4 // 8 to 11
).toString(16) // in hexadecimal
: ( // or otherwise a concatenated string:
[1e7] + // 10000000 +
-1e3 + // -1000 +
-4e3 + // -4000 +
-8e3 + // -80000000 +
-1e11 // -100000000000,
).replace( // replacing
/[018]/g, // zeroes, ones, and eights with
b // random hex digits
)
}
crypto.randomBytes(1)[0] % 16
function b(
a // placeholder
){
return a // if the placeholder was passed, return
? ( // a random number from 0 to 15
a ^ // unless b is 8,
crypto.randomBytes(1)[0] // in which case
% 16 // a random number from
>> a/4 // 8 to 11
).toString(16) // in hexadecimal
: ( // or otherwise a concatenated string:
[1e7] + // 10000000 +
-1e3 + // -1000 +
-4e3 + // -4000 +
-8e3 + // -80000000 +
-1e11 // -100000000000,
).replace( // replacing
/[018]/g, // zeroes, ones, and eights with
b // random hex digits
)
}
|
Make it secure at the cost of just a few bytes by replacing browser
node.js
|
@coolaj89 I don't have crypto.randomBytes in Chrome 46.0.2490.80 but there is crypto.getRandomValues
|
@coolaj89 I don't have |
And even smaller now:
b = a=>a?(a^Math.random()*16>>a/4).toString(16):([1e7]+-1e3+-4e3+-8e3+-1e11).replace(/[018]/g,b);
|
And even smaller now: |
Kiodaddy
edited |
I am having issue in 3rd file and i am not able to correct it . |
|
Great This works well thanks |
fergusean
edited |
in the annotated version: should be |
|
I try this code but this is not generating random UUIDs |
@coolaj89's you can golf that down a little:
([1e7]+-1e3+-4e3+-8e3+-1e11).replace(/[018]/g,b=>(b^crypto.rng(1)[0]%16>>b/4).toString(16))
crypto.rng is the same as crypto.randomBytes on a stock node.js build.
|
@coolaj89's you can golf that down a little: |
|
You guys are freaking insane...I love it... |
|
this was a wonderful thread to read |
@coolaj89 for the browser version you can shave off another char by replacing:
new Uint8Array(1)
with (not supported in all browsers, of course):
Uint8Array.of(0)
epistemex
edited |
@coolaj89 for the browser version you can shave off another char by replacing: with (not supported in all browsers, of course): |
@jussi-kalliokoski
For Nodejs, below change has to be done:
()=>([1e7]+-1e3+-4e3+-8e3+-1e11).replace(/[018]/g,a=>((a^crypto.randomBytes(1)[0]*16>>a/4).toString(16))[0])
|
@jussi-kalliokoski |
|
This is fantastic. |
|
Awesome. Is there a readable non-golfed version of this code? |
you can use this `${1e7}-${1e3}-${4e3}-${8e3}-${1e11}` to make it clear that it's a string
|
you can use this `${1e7}-${1e3}-${4e3}-${8e3}-${1e11}` to make it clear that it's a string |
Awesome. Is there a readable non-golfed version of this code?
Here's a more readable (verbose, RFC-compliant) version using crypto API:
var hex = [];
for (var i = 0; i < 256; i++) {
hex[i] = (i < 16 ? '0' : '') + (i).toString(16);
}
function makeUUID() {
var r = crypto.getRandomValues(new Uint8Array(16));
r[6] = r[6] & 0x0f | 0x40;
r[8] = r[8] & 0x3f | 0x80;
return (
hex[r[0]] +
hex[r[1]] +
hex[r[2]] +
hex[r[3]] +
"-" +
hex[r[4]] +
hex[r[5]] +
"-" +
hex[r[6]] +
hex[r[7]] +
"-" +
hex[r[8]] +
hex[r[9]] +
"-" +
hex[r[10]] +
hex[r[11]] +
hex[r[12]] +
hex[r[13]] +
hex[r[14]] +
hex[r[15]]
);
}
Here's a more readable (verbose, RFC-compliant) version using var hex = [];
for (var i = 0; i < 256; i++) {
hex[i] = (i < 16 ? '0' : '') + (i).toString(16);
}
function makeUUID() {
var r = crypto.getRandomValues(new Uint8Array(16));
r[6] = r[6] & 0x0f | 0x40;
r[8] = r[8] & 0x3f | 0x80;
return (
hex[r[0]] +
hex[r[1]] +
hex[r[2]] +
hex[r[3]] +
"-" +
hex[r[4]] +
hex[r[5]] +
"-" +
hex[r[6]] +
hex[r[7]] +
"-" +
hex[r[8]] +
hex[r[9]] +
"-" +
hex[r[10]] +
hex[r[11]] +
hex[r[12]] +
hex[r[13]] +
hex[r[14]] +
hex[r[15]]
);
} |
We can use coercion and exponential notation to get template string and save 7 bytes:
function(){return(""+1e7+-1e3+-4e3+-8e3+-1e11).replace(/1|0/g,function(){return(0|Math.random()*16).toString(16)})}