How to overwrite a variable every day (after 24 hours)?

Question

JavaScript

On the site I use the plugin to animate counters countUp.js
Here is the code that I use on the site

var options = {
  useEasing : true, 
  useGrouping : true, 
  separator : '', 
  decimal : '.', 
  prefix : '', 
  suffix : '' 
};
var developer_users = 75000;
var developer = new CountUp("developer", 0, developer_users, 0, 6.5, options);
var talent = new CountUp("talent", 0, 6, 0, 5, options);
var growth = new CountUp("growth", 0, 25, 0, 4, options);
var colleges = new CountUp("colleges", 0, 800, 0, 6, options);
developer.start();
talent.start();
growth.start();
colleges.start();

How can I make the developer_users variable increase every 24 hours, for example, by 3 and be, for example, 75003, after another 24 hours - 75006, and so on, and when the page is refreshed, the counter is not reset.
Here you can see a working example - outsoft.com
Thank you.

Answer 1

var developer_users = function() {

        var start = new Date('2015.10.10');
        var now = new Date();
        var days = Math.floor(((now - start) / 86400000));

        return 75000 + days * 3;
    }();

Answer 2

To prevent the counter from being reset when updating, you need LocalStorage
To update the counter every 24 hours, you need to do something like this script, which, for example, will check the date every second

setInterval(function () {
    var now = new Date();
    var hour = now.getHours();
    var min = getMinutes();
    // а дальше сравниваем с этолоном, например с 0 часов 0 минут 0 секунд
    // обновляем счетчик и сохраняем его в localStorage
}, 1000)

UPD: Anton B 's solution is better.

Answer 3

1) store on the server and transfer from the server
2) date function: f(x) = (dateNow-x).getDaysTotal()*3