Jamieson, Fausset and Brown on 2 Kings 11:2

2. Jehosheba--or Jehoshabeath (2Ch 22:11).

daughter of King Joram--not by Athaliah, but by a secondary wife.

stole him from among the king's sons which were slain--either from among the corpses, he being considered dead, or out of the palace nursery.

hid him ... in the bedchamber--for the use of the priests, which was in some part of the temple (2Ki 11:3), and of which Jehoiada and his wife had the sole charge. What is called, however, the bedchamber in the East is not the kind of apartment that we understand by the name, but a small closet, into which are flung during the day the mattresses and other bedding materials spread on the floors or divans of the sitting-rooms by day. Such a slumber-room was well suited to be a convenient place for the recovery of his wounds, and a hiding-place for the royal infant and his nurse.

2Ki 11:4-12. He Is Made King.