Hello coders, here are some exercises that would help you.

write function for each task 

Task

1. Define the "change color" function

hint:
obj.style.color
obj.style.backgroundColor 

2. Define the function of "changing width and height"

hint:
obj.style.width
obj.style.height 

3. Define the function of "hidden content"

Tip: 
obj.style.display ="none";

4. Define the function of "display content"

Tip: 
obj.style.display ="block";

5. Define the "unset" function

Tip: Use the confirm() confirmation box to confirm whether to cancel the setting. If so, restore all the above settings to their original values, otherwise do not operate.

6. When the corresponding button is clicked, the corresponding operation is performed, and the corresponding event is added to the button