10

what's the equivalent of this function in javascript:

http://php.net/manual/en/function.uniqid.php

Basically I need to generate a random ID that looks like: a4245f54345 and starts with a alphabetic character (so I can use it as a CSS id)

Brett Zamir
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Alex
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    I'm not going to close this as a duplicate, as php's `uniqid` doesn't seem to create GUID's (although that's what you would expect from it), but perhaps you can still find some help here: http://stackoverflow.com/questions/105034/how-to-create-a-guid-uuid-in-javascript – David Hedlund Feb 02 '11 at 08:54
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    Do you need it to be random, or can you simply use a sequential counter? i.e. 'a1', 'a2', etc... – Amir Feb 02 '11 at 09:01

8 Answers8

24

I have been using this...

I use it exactly as I would if it where PHP. Both return the same result.

function uniqid(prefix = "", random = false) {
    const sec = Date.now() * 1000 + Math.random() * 1000;
    const id = sec.toString(16).replace(/\./g, "").padEnd(14, "0");
    return `${prefix}${id}${random ? `.${Math.trunc(Math.random() * 100000000)}`:""}`;
};
Josh Merlino
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10

Try this (Work in php).

$prefix = chr(rand(97,121));  
$uniqid =  $prefix.uniqid(); // $uniqid = uniqid($prefix);

Try this for JavaScript::

var n = Math.floor(Math.random() * 11);
var k = Math.floor(Math.random() * 1000000);
var m = String.fromCharCode(n) + k;
Yukulélé
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Manish Trivedi
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5

All answers here (except phpjs) don't generate unique IDs because it's based on random. Random is not unique !

a simple solution :

window.unique_id_counter = 0 ;
var uniqid = function(){
    var id ;
    while(true){
        window.unique_id_counter++ ;
        id = 'uids_myproject_' + window.unique_id_counter ;
        if(!document.getElementById(id)){
            /*you can remove the loop and getElementById check if you 
              are sure that noone use your prefix and ids with this 
              prefix are only generated with this function.*/
            return id ;
        }
    }
}

It's easy to add dynamic prefix if it's needed. Just change unique_id_counter into an array storing counters for each prefixes.

DylannCordel
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2

The real question is, do you need the UUID to be RFC 4122 compliant? Your question seems to suggest you don't, so it wouldn't be too hard to create a function based simply on Math.random() to generate IDs like that. Plus it will be a lot faster than the phpJS implementation.

Jens Roland
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  • but what is RFC 4122 compliant? – Alex Feb 02 '11 at 09:33
  • @DylannCordel: Fair point, but neither are any of the other strategies suggested here. The PHP `uniqid()` method is essentially equivalent to `microtime()`, and any purely algorithmic uuid generator that runs in a browser or on a (load balanced, multi-instance) web server is going to have the potential for collisions -- UNLESS namespaced-by-server (clearly not the asker's intention) or verified against a centralized guid service. His 1 letter + 10 alphanumerics scheme yields a space of 95 quintillion or roughly 56bits of entropy. I wouldn't worry too much about collisions. – Jens Roland May 19 '15 at 15:18
2
<html>
<head>
<script type="text/javascript">
function generateSerial(len) {
    var chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXTZabcdefghiklmnopqrstuvwxyz";
    var string_length = 10;
    var randomstring = '';

    for (var x=0;x<string_length;x++) {

        var letterOrNumber = Math.floor(Math.random() * 2);
        if (letterOrNumber == 0) {
            var newNum = Math.floor(Math.random() * 9);
            randomstring += newNum;
        } else {
            var rnum = Math.floor(Math.random() * chars.length);
            randomstring += chars.substring(rnum,rnum+1);
        }

    }
    alert(randomstring);
}
generateSerial(8);
</script>
</head>
<body>

</body>
</html>

It's a bit convoluted, but you get the gist I'm sure!
Example: http://jsfiddle.net/Ng4tB/

Barrie Reader
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1
function uniqId(prefix) {
    if (window.performance) {
        var s = performance.timing.navigationStart;
        var n = performance.now();
        var base = Math.floor((s + Math.floor(n))/1000);
    } else {
        var n = new Date().getTime();
        var base = Math.floor(n/1000);
    }   
    var ext = Math.floor(n%1000*1000);
    var now = ("00000000"+base.toString(16)).slice(-8)+("000000"+ext.toString(16)).slice(-5);
    if (now <= window.my_las_uid) {
        now = (parseInt(window.my_las_uid?window.my_las_uid:now, 16)+1).toString(16);
    }
    window.my_las_uid = now;
    return (prefix?prefix:'')+now;
}

it is generated on "the same" priciple as PHP's uniqId() - specifically encoded time in microseconds.

kobliha
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  • Thanks! I wrote a test to compare your Javascript function with the output from PHP uniqid(). I found your answer to be more accurate. – Alex D Apr 30 '21 at 01:19
1

Underscore.js has a uniqueid() method
https://underscorejs.org/#uniqueId

_.uniqueId([prefix])
Generate a globally-unique id for client-side models or DOM elements that need one. If prefix is passed, the id will be appended to it.

_.uniqueId('contact_');  
=> 'contact_104'
Community
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Brad Kent
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0

Found this:

https://github.com/makeable/uuid-v4.js/blob/master/uuid-v4.js

and slightly modified to this:

function uniqid(length){
  var dec2hex = [];
  for (var i=0; i<=15; i++) {
    dec2hex[i] = i.toString(16);
  }

  var uuid = '';
  for (var i=1; i<=36; i++) {
    if (i===9 || i===14 || i===19 || i===24) {
      uuid += '-';
    } else if (i===15) {
      uuid += 4;
    } else if (i===20) {
      uuid += dec2hex[(Math.random()*4|0 + 8)];
    } else {
      uuid += dec2hex[(Math.random()*16|0)];
    }
  }

  if(length) uuid = uuid.substring(0,length);
  return uuid;
}

works great.

Luca Reghellin
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