Jack and the Beanstalk

Jack, a poor widow's son, trades their only cow for magic beans. His mother is upset, but the beans grow into a giant beanstalk. Jack climbs it, discovers a giant's castle, and steals treasures including coins, a golden chicken, and a harp. The giant chases him, but Jack cuts down the beanstalk, saving himself and his mother. They live happily ever after.

How did Jack manage to escape from the giant after taking the golden harp?

What did Jack do to ensure he and his mother were safe from the giant?