DOM Manipulation and Browser APIs Questions

Practical knowledge of the Document Object Model and browser application programming interfaces used to implement interactive user interfaces. Topics include querying and traversing elements, modifying classes and attributes, creating and removing elements, event handling and delegation, event propagation and capturing, safe insertion to avoid cross site scripting, efficient DOM updates to minimize reflows and repaints, layout thrashing and mitigation techniques, use of Fetch and storage APIs, cross browser considerations, and accessibility basics. Interviewers may ask for short implementations and discussion of performance and security trade offs.