JSFiddle - React, Tailwind, and code Playground

HTML

<title>Title</title>
<script src="engine.js"></script>
<script>
	setStartDate(2016, 06, 12);
</script>
<body>
    <p>start date: <script>document.write(getStartDate().toLocaleDateString())</script></p>
    <p>current day:
        <script>
            document.write(getCurrentEarningDay());
            document.write(" (\n");
            document.write(getCurrentDate());
        </script>
        )
    </p>
    <p>outrunning: 1 <script>document.write(formatDays(1))</script></p>
    <p>current step: <script>document.write(getStep())</script></p>
    <p>cash: <script>document.write(getTotalMoney())</script></p>
    <form id="formOne">
        <button onclick="addMoney(document.forms['formOne'].elements['addMoney'].value)">Add money</button>
        <input id="addMoney" size="3"/>
    </form>
    <br/>
    <button onclick="upStep(); location.reload();">Up step</button>
    <button onclick="downStep(); location.reload();">Down step</button>



</body>
</html>

JavaScript

/**
 * Created by holocaust on 21.07.16.
 */

var startDate;

function setStartDate(aYear, aMonth, aDay) {
    startDate = new Date(aYear, aMonth, aDay);
}
function getStartDate() {
    return startDate;
}
function getCurrentDate() {
    return new Date().toLocaleDateString();
}
function getCurrentEarningDay() {
    var startD = new Date(getStartDate()),
        currD = new Date(),
        numDays = (currD.getTime() - startD.getTime()) / (1000*60*60*24);
    numDays = Math.ceil(numDays);
    return numDays;
}
function getStep() {
    return +localStorage.getItem("step");
}
function upStep() {
    localStorage.setItem("step", +getStep() + 10);
}
function downStep() {
    if (+getStep() === 10) return null;
    localStorage.setItem("step", +getStep() - 10);
}
function formatDays(days) {
    if (days = 0 || days != 1) { return "days"; }
    else { return "day"; }
}

function addMoney(aMoney) {
   // if (aMoney === null || aMoney === undefined) return getTotalMoney();
    localStorage.setItem("money", +getTotalMoney() + +aMoney);
}
function getTotalMoney() {
    return +localStorage.getItem("money");
}