How do I show a complete list of available selections without having to type something first?

I have a field (well all of them really - I want this to be the default behaviour) where I want to show a list down of all available selections for a text field (i.e dropdown) but still have the ability for the user to type data into the field in order to select from the available options. 

Currently, once I put my cursor into the field, I have to start typing something into the text field for the list to appear. 

I want the list to appear immediately once the field is on focus without having to wait for the user to start data entering information. 

Is this possible?

  Discussion posts and replies are publicly visible