textbox onchange event in asp.net

Hi friends,
I want to call a function whenever theres text change in textbox using asp.net. I have tried with ontextchange() event but whenever I try to test it , it gives me error.

Please suggest me how can I call function on textchange in textbox.

ASP.NET Dynamic values in textarea or textbox fields.

Hi
How to append a value dynamically in a textarea from .vb page in which I am bringing value from database.