JSFiddle - React, Tailwind, and code Playground

HTML

<input type="text" id="count" />
<input type="button" id="calculate" value="Calculate" />

JavaScript

$(function(){
        var price = 10;
        var multiplier = 1;
        $('#calculate').click(function(){
            var count = parseInt($('#count').val());
            if(count > 10000){
                alert('Must be below 10000');
                return;
            }
            else if(count >= 1 && count <= 1000){
                multiplier = 1.2;
            }
            alert('Current price is ' + price + ' * ' + multiplier + ' = ' + getActualPrice());
        });
        
        function getActualPrice(){
            return price * multiplier;
        }
    });