When I view the source of your page I see 2 problems:

<SCRIPT src="Data/Sites/1/flash//tdee.js" type=text/javascript></SCRIPT>
<form method="post" style="width: 400px; height: 111.28%" name="tdeeform">

1. there is an extra / in the url for your script

2. You've embedded a <form element. In ASP.NET WebForms there can be one and only one form element on a page and one already exists (in layout.master it wraps all the content) so you cannot add one in the html content feature without breaking things.

Hope that helps,

Joe

You can use javascript, textboxes and buttons if it doesn't need to do postback but only does client side manipulation with javascript ie if your calculator is all javascript it would not necessarily need to postback, it could read the values from the textboxes and update a span or div with the results all client side with no postback, so the button click would not submit the form it would just invoke your javascript.

If you need to postback then you need to develop  a custom feature and use <asp:TextBox, <asp:Button etc, that way you are posting back using the form that already exists. To make it play nice with other features on the page you would wrap it in an UpdatePanel so the post back would use ajax and not affect other modules on the page. In that case it would seem easier to implement the calculator with server side code that executes on postback rather than javascript, you could use the hello world example as a starting point.

Hope that helps,

Joe

You would change the signature of your function to just function dosomething()

You would have to use unique ids on your textboxes and then you can get a reference using the id. Since jQuery is already included in the page you can use jquery to simplify the syntax

For example you have:

<input id="weight" size="5" name="weight" type="text" />

in js:

var weight = $("#weight").val();

read some jquery tutorials and you'll find how to do about anything you want.

without jquery the same example would be:

var weight = document.getElementById("weight").value;

Hope that helps,

Joe

Thanks for the beer!

Cheers,

Joe