Now, let's implement additional helper methods in our class. If we would like to know what the last element added to our stack was, we can use the peek method. This method will return the item from the top of the stack:
peek() { return this.items[this.items.length - 1];}
As we are using an array to store the items internally, we can obtain the last item from an array using length - 1 as follows:
For example, in the previous diagram, we have a stack with three items; therefore, the length of the internal array is 3. The last position used in the internal array is 2. As a result, the length - 1 ...
