だー

is, am, are

→ だ
auxiliary · informal Uncommon #19,675
is, am, are A drawn-out, emphatic spelling of だ, often used in exclamations or shouts.
JA: ここが出口だー!
EN: This is the exit!
Conjugation of だ

どけジャマだー!

Move! You’re in the way!

— One Cut of the Dead (2017)

ポルコ・ロッソだー!

It’s Porco Rosso!

— 紅の豚 (1992)

津波だー

It's a tsunami!

— 崖の上のポニョ (2008)

ハムだー

It's ham!

— 崖の上のポニョ (2008)

どこだー?

Where are you?

— パラサイト 半地下の家族 (2019)

ここだー!

Here it is!

— ピエロがお前を嘲笑う (2014)

もののけ姫だー!

It’s Princess Mononoke!

— もののけ姫 (1997)

俺だー

It's me!

— もののけ姫 (1997)

どうだー!

How about that!

— One Cut of the Dead (2017)

化け物だー

It's a monster!

— 天空の城ラピュタ (1986)