The type of irony used in the excerpt is dramatic irony.
Explanation:
Dramatic irony is related to a situation in which readers know and understand something that the characters themselves don't.<u> In this case, readers know Janet is in trouble for agreeing to wear the sweater.</u> We know she no longer has it because she exchanged it for the boots. As a matter of fact, we know she hated the sweater when she got it, and lied to Bobby saying she loved it.
<u>Bobby, however, is clueless to all that. He believes Janet still has the sweater, and is upset that she does not seem to appreciate the expensive gift. Bobby has no idea of the "pickle" Janet is in because of his demand. That is why this is an example of dramatic irony.</u>
