It is used to update the links automatically in the navigation list based on the scroll position. Means in a navigation bar we can update the links
in which our hidden content or image can be there. Here the data-spy="scroll" is use to add scroll on the webpage.
And than we have to target our navbar with the scrollable area so this we can do by adding data-target=".navbar"
also we have to take care about scrollable elements must match to the ID which is inside the navbar list .
Let’s understand this by the following program:-