Perform calculation inside textbox

Hi,

I'm wondering if anyone has come up with a way to perform calculations within a single TextBox or NumericTextBox?

For example, if I enter "3+5" as the text and then remove focus from the TextBox, I'd want the text value to update to "8". Similarly for other operations such as division or multiplication.

I've seen this behavior within other web applications ("You Need a Budget" comes to mind) and am wondering if a framework exists rather than building from scratch in javascript.

Thanks,

Jeff