(Probably easy) Help with javascript

I have a script that works great but I have a slight problem. I've added a new window.onload script outside of the one below, so now only the last one works. How can I run this code without using widow.onload?

<script type="text/javascript">
        window.onload = function calcPer() {
                document.getElementById("lbOverage").onchange = function calcPer() {
                document.getElementById("lblPercentOveralge").innerHTML = this.options[this.selectedIndex].text + '%';
                document.getElementById("lblOverageQty").innerHTML = Math.ceil((this.options[this.selectedIndex].text / 100) * document.getElementById("lblFinalOrderQuantity").innerHTML)
                var x = +document.getElementById("lblFinalOrderQuantity").innerHTML;
                var y = +document.getElementById("lblOverageQty").innerHTML;
                document.getElementById("lblActualProductionQuantity").innerHTML = x + y;
                document.getElementById("lblOverageQty").innerHTML = '(+' + document.getElementById("lblOverageQty").innerHTML + ')'
            }
        }
    </script>

Open in new window


<asp:ListBox ID="lbOverage" runat="server" CssClass="alwaysontop" onChange="calcPer();" Height="85px"

Open in new window


I have tried this:

<script type="text/javascript">
        function calcPer() {
                document.getElementById("lbOverage").onchange = function calcPer() {
                document.getElementById("lblPercentOveralge").innerHTML = this.options[this.selectedIndex].text + '%';
                document.getElementById("lblOverageQty").innerHTML = Math.ceil((this.options[this.selectedIndex].text / 100) * document.getElementById("lblFinalOrderQuantity").innerHTML)
                var x = +document.getElementById("lblFinalOrderQuantity").innerHTML;
                var y = +document.getElementById("lblOverageQty").innerHTML;
                document.getElementById("lblActualProductionQuantity").innerHTML = x + y;
                document.getElementById("lblOverageQty").innerHTML = '(+' + document.getElementById("lblOverageQty").innerHTML + ')'
            }
        }
    </script>

Open in new window


which works, however it does not work on the first selection. When a user makes a list box selection, it does nothing. Once they make a second selection, it runs as expected.
Mike MillerSoftware EngineerAsked:
Who is Participating?
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

RobOwner (Aidellio)Commented:
You're defining the onchange twice.  You only need to do it in the ListBox:
I've removed it from the code below
<script type="text/javascript">
function calcPer() {
	document.getElementById("lblPercentOveralge").innerHTML = this.options[this.selectedIndex].text + '%';
	document.getElementById("lblOverageQty").innerHTML = Math.ceil((this.options[this.selectedIndex].text / 100) * document.getElementById("lblFinalOrderQuantity").innerHTML);
	var x = +document.getElementById("lblFinalOrderQuantity").innerHTML;
	var y = +document.getElementById("lblOverageQty").innerHTML;
	document.getElementById("lblActualProductionQuantity").innerHTML = x + y;
	document.getElementById("lblOverageQty").innerHTML = '(+' + document.getElementById("lblOverageQty").innerHTML + ')';
}

    </script>

Open in new window

0
RobOwner (Aidellio)Commented:
Demo here; http://jsbin.com/cutodo/1/edit?html,js,console,output

javascript
function calcPer() {
	var me = document.getElementById('lbOverage');
	document.getElementById("lblPercentOveralge").innerHTML = me.options[me.selectedIndex].text + '%';
	document.getElementById("lblOverageQty").innerHTML = Math.ceil((me.options[me.selectedIndex].text / 100) * document.getElementById("lblFinalOrderQuantity").innerHTML);
	var x = +document.getElementById("lblFinalOrderQuantity").innerHTML;
	var y = +document.getElementById("lblOverageQty").innerHTML;
	document.getElementById("lblActualProductionQuantity").innerHTML = x + y;
	document.getElementById("lblOverageQty").innerHTML = '(+' + document.getElementById("lblOverageQty").innerHTML + ')';
}

Open in new window


rendered html used:
<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>JS Bin</title>
</head>
<body>
	<div id='lblPercentOveralge'></div>
	<div id='lblOverageQty'></div>
	<div id='lblFinalOrderQuantity'>5</div>
	<div id='lblOverageQty'>3</div>
	<div id='lblActualProductionQuantity'></div>
<select id="lbOverage" onchange="calcPer()">
	<option value="1">1</option>
	<option value="2">2</option>
	<option value="3">3</option>
	<option value="4">4</option>
	<option value="5">5</option>
	
	</select>

</body>
</html>

Open in new window

0

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
Mike MillerSoftware EngineerAuthor Commented:
Works like a charm. Nice catch. Thanks Rob!
0
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
JavaScript

From novice to tech pro — start learning today.

Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.