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 | |
| ) | |
| } |
| function b(a){return a?(a^Math.random()*16>>a/4).toString(16):([1e7]+-1e3+-4e3+-8e3+-1e11).replace(/[018]/g,b)} |
| 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" | |
| ] | |
| } |
(there's a walkthrough here, fwiw)
@jed thanks! :)
I was perusing the minified source of a website to see how they did something, came across this interesting way to create a GUID, and traced it back to here. I thought it was interestingly minified in the source I was looking at (with an insanely clever minifier!). Made me laugh when I saw that the original was golfed. 😆 A+ on the golfing, BTW! Clever minifier indeed--a clever human minifier. This was really fun to mentally chew on.
For funsies, here's a rough draft on a UUIDv7 generator:
[...Date.now().toString(16).padStart(12,0)].toSpliced(8,0,'-').join``+([-7e3]+-8e3+-1e11).replace(/[018]/g,b=>(b^crypto.rng(1)[0]%16>>b/4).toString(16))
right, you got it. the
1could be any other digit, really, it's just a placeholder, but the8was selected for its bitwise operation properties.