Generate unique random string with Javascript

Question

I am creating an app where I sometimes need to allow user to generate some random strings. I would like to force that to be generated in the following format:

xxxx-xxxx-xxxx

Where "x" is some number [0-9] or character [A-Z]. What would the most efficient way to do this? When generated, I would also need to check does it already exist in database so I am a little bit worried about the time which it would take.

Possible duplicate of [Create GUID / UUID in JavaScript?](http://stackoverflow.com/questions/105034/create-guid-uuid-in-javascript) — Matt Burland, Dec 20 '15 at 23:12
do you really need to check for duplicates? you're probably not that lucky, do the math... `Math.pow(36,12).toLocaleString()` — dandavis, Dec 20 '15 at 23:17
You say you want "random" but do you care that it is random? Do you only care that it is unique? — AgilePro, Dec 20 '15 at 23:17

score 19 · Answer 1 · answered May 20 '20 at 17:23

19

We can make it so simple like

require("crypto").randomBytes(64).toString('hex')

answered May 20 '20 at 17:23

yasarui

6,209
8
41
75

1

<3 awesome its short and simple. perfect code snippet. – Dean Van Greunen Nov 23 '20 at 12:43
crypto.randomBytes is deprecated. – jwilleke Feb 05 '22 at 12:31
not according to the nodejs docs https://nodejs.org/api/crypto.html – Qamar Stationwala Feb 16 '22 at 06:50

score 17 · Accepted Answer · edited May 23 '17 at 10:34

You can use crypto library.

var crypto = require('crypto');

//function code taken from http://blog.tompawlak.org/how-to-generate-random-values-nodejs-javascript
function randomValueHex (len) {
    return crypto.randomBytes(Math.ceil(len/2))
        .toString('hex') // convert to hexadecimal format
        .slice(0,len).toUpperCase();   // return required number of characters
}

var string = randomValueHex(4)+"-"+randomValueHex(4)+"-"+randomValueHex(4);
console.log(string);

Check these threads: Generate random string/characters in JavaScript

You can check if the field exists in the database. If it does, just generate a new token. Then check again. The probability of it existing is really low if you don't have large user base. Hence, probability of long loop of checks is low as well.

Generate unique random string with Javascript

2 Answers2