calculatetotal.js

var tax= 0.08;
var fee = 10;
var sinTax = 0.02;

(function f(item, price) {    
    var h = {
        'gas': function() {
            var total = price + price*tax + fee;
            alert(total);
        },
        'wine': function() {
            var total = price + price*tax + price*sinTax;
            alert(total);
        }
    };
    typeof h[item] == 'undefined' ? 
        (function() {
            var total = price + price*tax;  
            alert(total);    
        })() : h[item]();
})('milk', 100);