Textbox Textchanged event is not firing

Question

Hello All,

 

I have web form With Textboxes and Dropdowns.

 

I set client validation using Required Fields.

 

My Requirement is By using That Textbox content I need to generate dynamic code and store in another textbox.

 

Assume Textbox1 is main First Textbox, Textbox2 is  Generated code textbox.

 

I used OnTextChanged event in Textbox1 with AutoPostBack = True;

 

Its working fine as entering data. 

 

But Without give any data I am clicking on Submit button.

 

Then It focusing First textbox. And Then I am entering text and selecting next textbox 

 

OnTextChanged event is not firing.