Animation and Games JavaScript

What does this program do?

• Animates a ball by moving it down and to the right once every 20 milliseconds.

• Animates a ball by moving it up and to the right once every 20 milliseconds

• Animates a ball by moving it down and to the right every 20 seconds

• Animates a ball by moving it up and to the right once every 20 seconds

Which of the following statements are true about ball?

I – ball is a local variable

II – the ball variable in draw is different from the ball variable in start

III – ball is a global variable

IV – ball’s scope includes both start and draw

• III and IV

• I and II

• III only

• I, II, III, and IV

The following program animates a ball by setting a timer to move the ball across the screen. We want the animation to stop whenever the user clicks the mouse:

Which statement would stop the animation in this program?

• stopTimer(ball.move(2, 2));

• stopTimer(draw);

• stopTimer(draw());

• stopTimer(draw, 20);

We extend our draw function to include:

How many times will the ball be moved before the animation stops?

• 20

• 40

• 2

• 25

Which of the following are techniques that make our code more reusable?

I – Using constants instead of magic numbers

II – Using specific values in our functions rather than using parameters

III – Writing multiple functions that solve small subproblems rather than one function that solves the entire problem.

IV – Writing as few lines of code as possible

• I, II, and III

• II and IV

• I and III, and IV

• I, II, III, and IV

Which function has better reusability?

• 
• 

How many circles of radius 10 will fit vertically stacked in a window that has height 100? The circles should not overlap, the bottom of one circle should touch the top of the next circle.

• 10

• 20

• 5

• 100

This is a circle on our canvas named ball. What are the coordinates of point A?

• ball.getX(), ball.getY()

• ball.getRadius(), ball.getY()

• ball.getX(), ball.getY() + ball.getRadius()

• ball.getX() + ball.getRadius(), ball.getY()

What statement should we use to determine if ball is hitting the bottom edge of the window?

• 
• 
• 
• 

How can we determine if ball’s left edge is hitting a different shape on our canvas named box?

• 
• 
• 
•