A 17-year-old boy typed a note on a computer at an Apple Store, threatening to inflict “bloody death” by detonating a bomb there, prosecutors said.

Jason Barry was charged with making a terroristic threat at his arraignment yesterday in Staten Island Criminal Court.

Barry told police he was only joking when he typed the note under a friend’s father’s name on Monday and left it on the screen at the store at the Staten Island Mall.

The boy left the store, and someone at Apple discovered the note and called police.

Barry told police he meant to delete the letter but forgot, according to the criminal complaint.

But DA Daniel Donovan said the threat must be taken seriously in light of recent terrorist plots around the country.