var subtotal = 24.95; // A fake subtotal value to work with

function computeHandler() {
	var stateSelector, shippingSelector, discountText, resultText;
	var total, formatter, dollarAmount;
	
	// Gather the page elements we need to interact with
	stateSelector = document.getElementById('state');
	shippingSelector = document.getElementById('shipping');
	discountText = document.getElementById('discount');
	resultText = document.getElementById('result');
	
	// Start the computation
	if(discountText.value == 'SWEET10') {
		// 10% discount for entering a discount code
		total = 0.90 * subtotal;
	} else {
		// No discount to the subtotal
		total = subtotal;
	}
	
	if(shippingSelector.value == 'ground') {
		// Ground shipping is 8.95
		total = total + 8.95;
	} else if(shippingSelector.value == 'express') {
		// Express shipping is 14.95
		total = total + 14.95;
	}
	
	if(stateSelector.value == 'WI') {
		// Wisconsin customers get assessed a 5% sales tax
		total = 1.05*total;
	}
	
	// Create a number formatter.
	formatter = new Intl.NumberFormat('en-US', {
	  style: 'currency',
	  currency: 'USD',
	  minimumFractionDigits: 2,
	});
	
	// Present the result
	dollarAmount = formatter.format(total);
	resultText.textContent = 'Your total is ' + dollarAmount + '.';
}

function setup() {
    var subtotalSpan, computeButton;
    
    subtotalSpan = document.getElementById('subtotal');
    subtotalSpan.textContent = '$' + subtotal;
    
    computeButton = document.getElementById('compute');
    computeButton.addEventListener('click',computeHandler,false);
}

window.addEventListener('load',setup,false);