17.2.3. Event Listener (Observer)

Try these first

1. 1.

   What is an event listener?

   Hint

   Think about user interactions in an application.

2. 2.

   What is a callback function?

   Hint

   What happens when you click a button?

3. 3.

   What is the primary function of an event listener?

   • To initiate an event
   • To respond to an event
   • To stop an event

   Hint

   Think about what happens after an event occurs.

4. 4.

   True or False: Event listeners can only be used in web applications.

   • True
   • False

   Hint

   Consider different programming languages and platforms.

5. 5.

   Design an event listener in JavaScript that changes the background color of a webpage when a button is clicked. Provide both the HTML and JavaScript.

   Hint

   Think about how to connect the button and the event action.

6. 6.

   Write a small Python Tkinter application with a button that uses an event listener to print a message when clicked.

   Hint

   Remember to set up the main loop for the GUI.