When a Todo property updates, you still must create a new Array of Todos and assign a new reference. This lesson walks you through refactoring from the current approach to the immutable approach.
Nice videos! -- I just have a question about the toggle todo immutability approach. When before you reconstruct the todos array with slice(0,1) and etc, the todo in question whose status is set to completed by todo.toggle(), would't this mean that we are changing its state, an act that we try to avoid?