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

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("");

Answer 2

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/

Answer 3

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);
};

Answer 4

I have done this way

function uniqeId() {
   var ranDom = Math.floor(new Date().valueOf() * Math.random())
   return _.uniqueId(ranDom);
}

Answer 5

In ES6:

const ID_LENGTH = 36
const START_LETTERS_ASCII = 97 // Use 64 for uppercase
const ALPHABET_LENGTH = 26

const uniqueID = () => [...new Array(ID_LENGTH)]
  .map(() => String.fromCharCode(START_LETTERS_ASCII + Math.random() * ALPHABET_LENGTH))
 .join('')

Example:

 > uniqueID()
 > "bxppcnanpuxzpyewttifptbklkurvvetigra"

Answer 6

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.