Untitled

<!DOCTYPE html>
<html>
<body>
<script>
var cost;
var costNumber = 0;
var cash;
var cashNumber = 0;
var cashBack;
var costText = ("Cost of merchandise");
var cashText = ("Cash Paid");


function costPrompt() {
dataPrompt(cost, costText, costNumber, costPrompt);
}

function cashPrompt() {
dataPrompt(cash, cashText, cashNumber, cashPrompt);
}

function dataPrompt(x, y, z, a) {
x = prompt (y);
z = parseFloat(x);
if (isNaN(z)) {
    alert ("That's not a number, cumface. Try again.");
    a();
}
}

costPrompt();

cashPrompt();

console.log ("cashNumber " + cashNumber);
console.log ("costNumber " + costNumber);
</script>
</body>
</html>