How to call Java Script function in ASP.NET TextBox OnTextChanged Event

Question

Hai,
I have two text boxes named txtDOB (Date Of Birth), and txtDOJ (Date of Join)
i have to compare both text boxes DOJ is not greater than DOB..
For this i wrote a java script function, my problem is how to cal that
java script function in txtDoJ's "OnTextChanged Event ",

If u know help me..

Thanks and Regards,
Honey.