Create a unique number with javascript time

Question

I need to generate unique id numbers on the fly using javascript  In the past  I ve done this by creating a number using time   The number would be made up of the four digit year  two digit month  two digit day  two digit hour  two digit minute  two digit second  and three digit millisecond  So it would look something like this  20111104103912732      this would give enough certainty of a unique number for my purposes   It s been a while since I ve done this and I don t have the code anymore  Anyone have the code to do this  or have a better suggestion for generating a unique ID

User · Answer

This creates an almost guaranteed unique 32 character key client side, if you want just numbers change the "chars" var.

var d = new Date().valueOf();
var n = d.toString();
var result = '';
var length = 32;
var p = 0;
var chars = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';

for (var i = length; i > 0; --i){
    result += ((i & 1) && n.charAt(p) ? '<b>' + n.charAt(p) + '</b>' : chars[Math.floor(Math.random() * chars.length)]);
    if(i & 1) p++;
};

https://jsfiddle.net/j0evrdf1/1/

User · Answer

let uuid     new Date   getTime    toString 36        Date now     Math random   toString    split      join           sample result  k3jobnvt 15750033412250 18299601769317408

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Always get unique Id in JS   function getUniqueId       return  new Date   getTime    toString 36    new Date   getUTCMilliseconds       getUniqueId         Call the function  ------------results like     ka2high4264      ka2hj115905      ka2hj1my690      ka2hj23j287      ka2hj2jp869

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Maybe even better would be to use getTime   or valueOf    but this way it returns unique plus human understandable number  representing date and time    window getUniqNr   function       var now   new Date       if  typeof window uniqCounter      undefined   window uniqCounter   0     window uniqCounter       var m   now getMonth    var d   now getDay       var h   now getHours    var i   now getMinutes       var s   now getSeconds    var ms   now getMilliseconds      timestamp   now getFullYear   toString         m  lt   9    0          m toString        d  lt   9    0          d toString         h  lt   9    0          h toString         i  lt   9    0          i toString         s  lt   9    0          s toString         ms  lt   9    00     ms  lt   99    0           ms toString        window uniqCounter      return timestamp     window getUniqNr

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From investigating online I came up with the following object that creates a unique id per session           window mwUnique            prevTimeId   0          prevUniqueId   0          getUniqueID   function                try                   var d new Date                    var newUniqueId   d getTime                    if  newUniqueId    mwUnique prevTimeId                      mwUnique prevUniqueId   mwUnique prevUniqueId   1                  else                       mwUnique prevTimeId   newUniqueId                      mwUnique prevUniqueId   0                                    newUniqueId   newUniqueId        mwUnique prevUniqueId                  return newUniqueId                                                 catch e                    mwTool logError  mwUnique getUniqueID error     e message                                                     It maybe helpful to some people   Cheers  Andrew

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This should do    var uniqueNumber   new Date   getTime       milliseconds since 1st Jan  1970

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Assumed that the solution proposed by  abarber it s a good solution because uses  new Date    getTime   so it has a windows of milliseconds and sum a tick in case of collisions in this interval  we could consider to use built-in as we can clearly see here in action   Fist we can see here how there can be collisions in the 1 1000 window frame using  new Date    getTime     console log   new Date    getTime      console log   new Date    getTime     VM1155 1 1469615396590 VM1155 1 1469615396591 console log   new Date    getTime      console log   new Date    getTime     VM1156 1 1469615398845 VM1156 1 1469615398846 console log   new Date    getTime      console log   new Date    getTime     VM1158 1 1469615403045 VM1158 1 1469615403045   Second we try the proposed solution that avoid collisions in the 1 1000 window   console log  window mwUnique getUniqueID      console log  window mwUnique getUniqueID       VM1159 1 14696154132130 VM1159 1 14696154132131   That said we could consider to use functions like the node process nextTick that is called in the event loop as a single tick and it s well explained here  Of course in the browser there is no process nextTick so we have to figure how how to do that  This implementation will install a nextTick function in the browser using the most closer functions to the I O in the browser that are setTimeout fnc 0   setImmediate fnc   window requestAnimationFrame  As suggested here we could add the window postMessage  but I leave this to the reader since it needs a addEventListener as well  I have modified the original module versions to keep it simpler here   getUniqueID    c   gt     if typeof nextTick    undefined   nextTick    function window  prefixes  i  p  fnc        while   fnc  amp  amp  i  lt  prefixes length            fnc   window prefixes i       equestAnimationFrame              return  fnc  amp  amp  fnc bind window      window setImmediate    function fnc   window setTimeout fnc  0        window   r webkitR mozR msR oR  split       0    nextTick      gt       return c   new Date    getTime                So we have in the 1 1000 window   getUniqueID function c    console log c      getUniqueID function c    console log c       undefined VM1160 1 1469615416965 VM1160 1 1469615416966

User · Answer

Here s what I do when I want something smaller than a bunch of numbers - change base   var uid    new Date   getTime    toString 36

User · Answer

The shortest way to create a number that you can be pretty sure will be unique among as many separate instances as you can think of is    Date now     Math random     If there is a 1 millisecond difference in function call  it is 100  guaranteed to generate a different number  For function calls within the same millisecond you should only start to be worried if you are creating more than a few million numbers within this same millisecond  which is not very probable   For more on the probability of getting a repeated number within the same millisecond see https   stackoverflow com a 28220928 4617597

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In 2020  you can use the in-browser Crypto API to generate cryptographically strong random values  function getRandomNumbers       const typedArray   new Uint8Array 10     const randomValues   window crypto getRandomValues typedArray     return randomValues join         console log getRandomNumbers        1857488137147725264738   both Uint8Array and Crypto getRandomValues are supported on all major browsers  including IE11

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Using toString 36   slightly slow  here is the faster and unique solution  new Date   getUTCMilliseconds   toString      quot - quot    Date now      quot - quot    filename replace   s  g   quot - quot   toLowerCase

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use this for creating unique number in javascript  var uniqueNumber  new Date   getTime    toString 36     It really works

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I use  Math floor new Date   valueOf     Math random      So if by any chance the code is fired at the same time there is also a teeny chance that the random numbers will be the same

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Since milliseconds are not updated every millisecond in node  following is an answer  This generates a unique human readable ticket number  I am new to programming and nodejs  Please correct me if I am wrong   function get2Digit value    if  value length    1  return  0         value  else return value       function get3Digit value    if  value length    1  return  00         value  else return value       function generateID         var d   new Date        var year   d getFullYear        var month   get2Digit d getMonth     1       var date   get2Digit d getDate         var hours   get2Digit d getHours         var minutes   get2Digit d getMinutes         var seconds   get2Digit d getSeconds         var millSeconds   get2Digit d getMilliseconds         var dateValue   year        month        date      var uniqueID   hours        minutes        seconds        millSeconds       if  lastUniqueID     false     lastUniqueID  lt  uniqueID  lastUniqueID   uniqueID      else lastUniqueID   Number lastUniqueID    1      return dateValue        lastUniqueID

User · Answer

in reference to  Marcelo Lazaroni solution above  Date now     Math random     returns a number such as this 1567507511939 4558  limited to 4 decimals   and will give non-unique numbers  or collisions  every 0 1    adding toString   fixes this  Date now     Math random   toString    returns  15675096840820 04510962122198503   a string   and  is further so  slow  that you never get the  same  millisecond  anyway

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I have done this way  function uniqeId        var ranDom   Math floor new Date   valueOf     Math random       return   uniqueId ranDom

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In ES6   const ID LENGTH   36 const START LETTERS ASCII   97    Use 64 for uppercase const ALPHABET LENGTH   26  const uniqueID        gt      new Array ID LENGTH      map      gt  String fromCharCode START LETTERS ASCII   Math random     ALPHABET LENGTH     join       Example     gt  uniqueID     gt   bxppcnanpuxzpyewttifptbklkurvvetigra

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Easy and always get unique value    const uniqueValue    new Date    getTime     Math trunc 365   Math random       OUTPUT LIKE THIS     1556782842762

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I came across this question while trying to find a simple UID generation technique that was also sortable  so I can order by uid and items will appear in order of creation   uid generation   The major problem with most  all   of the solutions here is that they either rely on millisecond accuracy  at best     clashes    or a pseudo-random number    clashes     amp  amp  non-sortable     Technique below uses micro-second precision where available  i e  not where fingerprinting-resistance techniques are in play  e g  firefox  combined with an incrementing  stateful suffix  Not perfect  or particularly performant for large numbers of IDs  see example with 1 000 000 below   but it works and is reversible   x000D   x000D     return a uid  sortable by creation order let increment  let tuidPrev   const uid    uidPrev    gt         get current time to microsecond precision  if available  and remove decimals   const tuid     performance timing navigationStart   performance now      1000         convert timestamp to base36 string      toString 36         previous uid has been provided  stateful    if  uidPrev        tuidPrev   uidPrev slice 0  10       increment   uidPrev length  gt  10   parseInt uidPrev slice 10   36    0            if tuid is changed reset the increment   if  tuid     tuidPrev        tuidPrev   tuid      increment   0            return timed uid   suffix  4 36 values      very unique id    return tuid     000     increment    toString 36   slice -4          EXAMPLE  check the console   const iterations   1000000  const uids       const uidMap       const timeMap      const microMap       let time   performance now    for  let i   0  i  lt  iterations  i        const id   uid      uids push id     uidMap id    i    timeMap Date now      i    microMap performance now      i     console log  Time taken    performance now   - time ms    console log  Unique IDs    Object keys uidMap  length toLocaleString     console log  Clashing timestamps     iterations - Object keys timeMap  length  toLocaleString     console log  Clashing microseconds     iterations - Object keys microMap  length  toLocaleString     console log  Sortable     uids slice   sort   find  id  i    gt  uids i      id   x000D   x000D   x000D

User · Answer

simple solution I found var today   new Date   valueOf    console log  today

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This can be achieved simply with the following code   var date   new Date    var components         date getYear        date getMonth        date getDate        date getHours        date getMinutes        date getSeconds        date getMilliseconds       var id   components join

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if you want a unique number after few mili seconds then use Date now    if you want to use it inside a for loop then use Date now   and Math random   together  unique number inside a for loop  function getUniqueID        for var i   0  i lt  5  i          console log Date now        Math random   100000  toFixed       getUniqueID     output   all numbers are unique  15598251485988384 155982514859810330 155982514859860737 155982514859882244 155982514859883316  unique number without Math random    function getUniqueID            for var i   0  i lt  5  i              console log Date now              getUniqueID     output   Numbers are repeated  1559825328327 1559825328327 1559825328327 1559825328328 1559825328328

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Posting this code snippet here for my own future reference  not guaranteed but satisfactory  unique  enough       a valid floating number window generateUniqueNumber   function         return new Date   valueOf     Math random           a valid HTML id window generateUniqueId   function         return       new Date   valueOf     Math random   toFixed 16  substring 2

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This returns unique value even when inside fast loop  ofcourse this can be improved much more  x000D   x000D  const getUniqueValue    strength   2  int false    gt             const u        gt   Math random     10000  toString   replace                   let r                for  let i 0  i  lt  strength  i              r    u                   return  int    parseInt r    r      1 2 3 5 6 7 8 9 10  map item   gt  console log getUniqueValue      x000D   x000D   x000D

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A better approach would be   new Date   valueOf      instead of   new Date   getUTCMilliseconds      valueOf   is  most likely  a unique number   http   www w3schools com jsref jsref valueof date asp

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function UniqueValue d           var dat e   new Date            var uniqu e     Math random    1000       slice -4           dat e   dat e toISOString   replace    0-9  g      replace dat e getFullYear   uniqu e           if d  dat e              dat e   UniqueValue dat e           return dat e          Call 1  UniqueValue  0    Call 2  UniqueValue UniqueValue  0       will be complex   Sample Output   for var i  0 i lt 10 i     console log UniqueValue UniqueValue  0        60950116113248802  26780116113248803  53920116113248803  35840116113248803  47430116113248803  41680116113248803  42980116113248804  34750116113248804  20950116113248804  03730116113248804

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To get a unique number  function getUnique        return new Date   getTime   toString     window crypto getRandomValues new Uint32Array 1   0        or  function getUniqueNumber        const now   new Date        return Number           now getFullYear            now getMonth            now getDate            now getHours            now getMinutes            now getUTCMilliseconds            window crypto getRandomValues new Uint8Array 1   0        join  quot  quot        Example  getUnique    quot 15951973277543340653840 quot   for  let i 0  i lt 5  i         console log  getUnique        15951974746301197061197 15951974746301600673248 15951974746302690320798 15951974746313778184640 1595197474631922766030  getUniqueNumber   20206201121832230  for  let i 0  i lt 5  i         console log  getUniqueNumber        2020620112149367 2020620112149336 20206201121493240 20206201121493150 20206201121494200  you can change the length using  new Uint8Array 1  0     or new Uint16Array 1  0     or new Uint32Array 1  0

User · Answer

This also should do    function         var uniquePrevious   0      uniqueId   function             return uniquePrevious

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If you just want a unique-ish number  then  var timestamp   new Date   getUTCMilliseconds      would get you a simple number  But if you need the readable version  you re in for a bit of processing   var now   new Date     timestamp   now getFullYear   toString       2011 timestamp     now getMonth  lt  9    0          now getMonth   toString       JS months are 0-based  so  1 and pad with 0 s timestamp      now getDate  lt  10     0          now getDate   toString       pad with a 0     etc    with  getHours    getMinutes    getSeconds    getMilliseconds

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let now   new Date    let timestamp   now getFullYear   toString    let month   now getMonth     1  timestamp     month  lt  10    0          month toString    timestamp     now getDate    lt  10    0          now getDate   toString    timestamp     now getHours    lt  10    0          now getHours   toString    timestamp     now getMinutes    lt  10    0          now getMinutes   toString    timestamp     now getSeconds    lt  10    0          now getSeconds   toString    timestamp     now getMilliseconds    lt  100    0          now getMilliseconds   toString

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This performs faster than creating a Date instance  uses less code and will always produce a unique number  locally    function uniqueNumber         var date   Date now            If created at same millisecond as previous     if  date  lt   uniqueNumber previous            date     uniqueNumber previous        else           uniqueNumber previous   date             return date     uniqueNumber previous   0    jsfiddle  http   jsfiddle net j8aLocan   I ve released this on Bower and npm  https   github com stevenvachon unique-number  You could also use something more elaborate such as cuid  puid or shortid to generate a non-number

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function getUniqueNumber          function shuffle str            var a   str split              var n   a length          for var i   n - 1  i  gt  0  i--                var j   Math floor Math random      i   1                var tmp   a i               a i    a j               a j    tmp                    return a join                var str   new Date   getTime      Math random   999  1000  toFixed     string     return Number parseInt shuffle str

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100  guaranteed to generate a different number      x000D   x000D  var Q  x000D  Q       x000D  Q timeInterval  x000D   x000D  function genUniqueID kol    x000D   Q timeInterval   setTimeout function     x000D    document querySelector   demo   innerHTML    new Date   valueOf       lt br gt    x000D    kol--  x000D    if  kol  gt  0    x000D     genUniqueID kol   x000D      x000D      document querySelector   i2   value   x000D    x000D   lt div gt  lt input id  i1  type  number  value  5  style  width  60px   gt  lt label gt  - Amount lt  label gt  lt br gt  x000D       lt input id  i2  type  number  value  10  style  width  60px   gt  lt label gt  - Millisecond interval lt  label gt  lt  div gt  lt br gt  x000D   lt div gt  x000D       lt button onclick  genUniqueID document querySelector   i1   value    gt Start lt  button gt  x000D       lt button onclick  clearTimeout Q timeInterval    gt Stop lt  button gt  x000D       lt button onclick  document querySelector   demo   innerHTML       gt Clear lt  button gt  x000D   lt  div gt  lt br gt  x000D   lt div id  demo  gt  lt  div gt  x000D   x000D   x000D

[javascript] Create a unique number with javascript time

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