📄️ Algorithms
Front End Engineers are also Software Engineers after all, and it's an expectation that Front End Engineers have basic competency in algorithms and data structures. It is possible and reasonable that you will be asked to solve algorithmic questions during your front end interviews and most likely you will be expected to use JavaScript.
📄️ Utility functions
These are the front-end version of LeetCode questions, but with less emphasis on complicated algorithms and more focused on practical use cases. However, they could also be questions simply being the same LeetCode problem but you are required to answer in JavaScript.
📄️ Build user interfaces
Many Front End Engineers spend a lot of time building UI, and building a UI component is a good way to assess someone's familiarity in the three biggest aspects of front end - HTML, JS, CSS.