Colloquial way of asking 'where?'—used to inquire about a place or location.
財布、どこだって？さっきテーブルの上にあったよ。
Where's my wallet? It was on the table a moment ago.
ここ、どこだって？見たことのない場所だ。
Where is this? It's a place I've never seen before.
Means 'anywhere' or 'everywhere'—equivalent to どこでも, used colloquially and sometimes for emphasis.
どこだって行けるよ、君が行きたいところに合わせる。
I can go anywhere; I'll go where you want to go.
最近はどこだってネットがつながるから便利だ。
These days it's convenient because you can get online anywhere.
どこだって同じだ、重要なのはやり方だ。
Anywhere is the same; what matters is the method.