Josiah's immediate reaction to the words of Huldah the prophetess was

When Josiah heard the words of Huldah the prophetess, he tore his clothes in distress and immediately ordered the reading of the book of the law in the hearing of all the people. He also made a covenant to follow the Lord and keep his commandments, and began a campaign to remove all the idols and false gods from the land, including those in the temple. Therefore, Josiah's immediate reaction to the words of Huldah was reading the book of the law and taking action to follow it.