When you build interactive canvas applications using Konva.js, responding to user actions is essential for creating engaging experiences. You can listen for a wide range of events on shapes, such as clicks, taps, mouse movements, and double-clicks. Konva.js uses an event system similar to DOM events, but it is tailored for the canvas and its own node hierarchy.

Event propagation in Konva.js flows from the specific shape that received the event up through its parent groups, layers, and finally the stage. This means that if multiple shapes overlap and a user clicks, only the topmost visible shape under the pointer receives the event first. If you attach an event listener to a parent group or the stage, it can catch events from any descendant shapes, which is useful for centralized event management. However, you should be mindful to avoid unwanted side effects from bubbling events, such as accidentally triggering actions on parent nodes when only a child shape is intended to respond.

Best practices for managing user input in Konva.js include:

• Attaching event listeners directly to the shapes when you want specific responses;
• Using event delegation on groups or layers for managing many similar shapes;
• Always considering event propagation to prevent conflicts.

For custom behaviors like selection or hover effects, update only the relevant shape properties and redraw the affected layer for optimal performance. Remember to use the on() method provided by Konva nodes to register event handlers, and to clean up listeners if shapes are removed to prevent memory leaks.