Generates (locally) unique incrementing numbers

Usage no npm install needed!

<script type="module">
  import getTlidEncoderDecoder from '';



Given a supplied epoch it will generate you TLId, which is a word I just invented!

What is a TLId? It stands for Time Local Id and gives you a reference based on a timestamp that is locally unique.


  • Timestamps will nearly always be unique, whereas these are guarenteed to be unique.
  • The are shorter than timestamps (though not by a lot).
  • You can extract the timestamp that the TLId was generated.
  • If you want them ordered by generation time, you do not need to convert them back to timestamps beforehand.

Here's how you use it:

// Use one character (32 bit number) to ensure uniqueness within a millisecond
var uniquenessPerMillisecond = 1;
// As close as possible (but lower) than the lowest date to give shorter Id's
var epoch = new Date(1970,0,1).getTime();

// Get the TLId Encoder / Decoder
var encoderDecoder = getTLIdEncoderDecoder(epoch,uniquenessPerMillisecond);

// Encode a date into a unique string
var dates = [
  encoderDecoder.encode(new Date(1980,1,6).getTime()),
  encoderDecoder.encode(new Date(1981,3,15).getTime()),
  encoderDecoder.encode(new Date(1986,8,9).getTime()),
  encoderDecoder.encode(new Date(1983,10,3).getTime()),
  encoderDecoder.encode(new Date(1982,0,6).getTime())

// Get the dates it was encoded
var originalTimestamps =;

// Sort them in date order
var sortedDates = dates.sort(encoderDecoder.sort);

Source Code

Source code is prepared using Browserify which is also compatible with Node.JS. There is a UMD bundle which can be used with AMD or a vanilla browser (where it will export a global called called getTLIdEncoderDecoder.