visible/invisible combo box with text box

I'm trying to make an interactive text box with combo box.

The combo box shall be invisible until I push/click the text box.

When I push/click the text box, the combo box shall be visible.

If I select an item in the combo box, the item shall be input to the text box, and then the combo box shall be invisible.

After I push/click the text box(the combo box will be visible), If I click any part of the document other than the text box, the visible combo box shall disappear.

How should I do?

Thanks, in advance.