lab4

<!DOCTYPE html>
<html>
<head>
<title>CIS 223 Lab Assignment #4</title>

</head>

<body>
<h2>This is the lab assignment #4</h2>
<form>
<table>
<h4>
<tr>
<td>Name</td><td><input type="text" id="name" size=20 /></td></tr>
<tr>
<td>Hours Worked</td><td><input type="text" id="hours" size=8 /></td></tr>
<tr>
<td>Pay Rate</td><td><input type="text" id="rate" size=8 /></td></tr>
<tr>
<td>Gross Pay</td><td><input type="text" id="grossPay" size=8 DISABLED /></td></tr>
<tr>
<td>Tax</td><td><input type="text" id="tax" size=8 DISABLED /></td></tr>
<tr>
<td>Net Pay</td><td><input type="text" id="netPay" size=8 DISABLED /></td></tr>
</table>
<p><input type="button" value="Calculate" id="calculate" /></p>
</form>
<script>
    var hours = 0;
    var rate = 0.0;
    var grossPay = 0.0;
    var tax = 0.0;
    var netPay = 0.0;


    function process() {
		grossPay = hours * rate;
		document.getElementById("grossPay").value = grossPay;

		tax = grossPay * 0.10;
		document.getElementById("tax").value = tax;

		netPay = grossPay - tax;
		document.getElementById("netPay").value = netPay;

     }


      function verifyValues()
      {
	    hours = document.getElementById("hours").value;
	    rate = document.getElementById("rate").value;

	    try {
	        if(hours === "")
	        throw "Hours or Rate should not be blank"

	        if(rate === "")
	        throw "Hours or Rate should not be blank"

			if (hours < 0)
			    throw "Please enter positive value for hours";

			if (rate < 8.25)
			    throw "Minimum wage is $8.25 per hour";

	    }
		catch(error) {
			window.alert(error)
			return false;
		}

		process();

      }

      // add backward compatible event listener to Submit button
      var submitButton = document.getElementById("calculate");
      if (submitButton.addEventListener) {
        submitButton.addEventListener("click", verifyValues, false);
      }
	  else if (submitButton.attachEvent)  {
        submitButton.attachEvent("onclick", verifyValues);
      }


	</script>
</h4>
</body>
</html>