I am a designer with a 1-2 years experience with front-end development. I don't offer that service very often as a freelancer, so I wanted to get some advice on a freelance situation.
I developed a one-page website for a client. The client gave me a desktop view of the design and an example of how they wanted the navigation to work; that was it. I created the fully-responsive website, everything working fully.
They wanted to add a new section to the page that was not a part of the original design they gave me. Now they want the intro type to fade away as the user scrolls in order to stop the overlapping of the sticky navigation (this was not part of the original ask) and finally they are wanting me to animate the hamburger icon to an "x" a certain way when the mobile navigation opens on a phone. I feel like they just keep tacking on things that I was not originally told about.
Is this part of the freelance development process, continually adding new behaviors and more and more jQuery?
Should I be telling them this stuff will cost more because it was not a part of the original plan? Do developers build a cushion in the budget (let's say an extra $500) to allow for this type of stuff?
Thank you for help!