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 digi

Answer 1

simple solution I found

var today = new Date().valueOf();

console.log( today );

Answer 2

This also should do:

(function() {
    var uniquePrevious = 0;
    uniqueId = function() {
        return uniquePrevious++;
    };
}());

Answer 3

This should do :

var uniqueNumber = new Date().getTime(); // milliseconds since 1st Jan. 1970

Answer 4

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 < uniqueID) lastUniqueID = uniqueID;
    else lastUniqueID = Number(lastUniqueID) + 1;
    return dateValue + "" + lastUniqueID;
}

Answer 5

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 => {
 if(typeof(nextTick)=='undefined')
nextTick = (function(window, prefixes, i, p, fnc) {
    while (!fnc && i < prefixes.length) {
        fnc = window[prefixes[i++] + 'equestAnimationFrame'];
    }
    return (fnc && fnc.bind(window)) || window.setImmediate || function(fnc) {window.setTimeout(fnc, 0);};
})(window, 'r webkitR mozR msR oR'.split(' '), 0);
 nextTick(() => {
   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

Answer 6

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 <= 9 ? '0' : '') + m.toString()
  +( d <= 9 ? '0' : '') + d.toString() 
  + (h <= 9 ? '0' : '') + h.toString() 
  + (i <= 9 ? '0' : '') + i.toString() 
  + (s <= 9 ? '0' : '') + s.toString() 
  + (ms <= 9 ? '00' : (ms <= 99 ? '0' : '')) + ms.toString() 
  + window.uniqCounter; 

  return timestamp;
};
window.getUniqNr();