onChange Event in Attribute

[Swabedoo]

Hallo,

i want to catch an onchange Event with JavaScript in an Attribute Selectbox because the actual price is calculated per squaremeters in the product description and if the visitor select an option with extra charge the new price should be displayed.
Hope someone has a solution for me.

Greetings, Swabedoo

[Swabedoo]

Maybe someone can tell me, in which File the HTML-Output for the Attributes is generated.