asp.net - How can I fill textboxes using dropdownlist without postback? -

I have an asp.net dropdownload entry for hours and minutes of the day. Should I choose the time shown in Texx Box, can it be done without postback? Ajax Control Toolkit is a combo box in dropdownlists and text in Microsoft. Enables the box task to select from the combo box or writing directly as a text box. Apart from this, only able to restrict free writing to the item or anything in the combo box.