JavaScript and Graphics

A store has 20 apples in its inventory. How can you store this information in a JavaScript variable?

• var numApples == 20;

• 20 = numApples;

• var numApples = 20;

• var num apples = 20;

You want to read input from the user to know how many apples they would like to buy. Which statement should you use to read in a number from the user?

• var applesToBuy = readLine("How many apples would you like? ");

• var applesToBuy = println("How many apples would you like? ");

• var applesToBuy = readInt("How many apples would you like? ");

• var applesToBuy = nextInt("How many apples would you like? ");

You are splitting up all of your apples equally between 3 people. Which statement below will calculate how many apples will be left over?

• var leftOver = numApples / 3;

• var leftOver = 3 / numApples;

• var leftOver = numApples % 3;

• var leftOver = 3 % numApples;

In a graphics canvas, what are the coordinates of the bottom right corner of the window?

• 0, 0

• 0, getWidth()

• getHeight(), getWidth()

• getWidth(), getHeight()

What are the coordinates of the center of the window?

• getWidth(), getHeight()

• getWidth() / 2, getHeight() / 2

• getHeight() - getWidth(), getWidth() - getHeight()

• getHeight() / 2, getWidth() / 2

In the following code:

var size = 20;

var x = 100;

var y = 200;

var ball = new Circle(size);

ball.setPosition(x, y);

What is the meaning of the x variable?

• The x coordinate of the center of the circle

• The x coordinate of the left edge of the circle

• The radius of the circle

• The position of the circle

The following program should draw a circle on the screen

1 function start(){

2 var circle = new Circle(40);

3 circle.setPosition(getWidth() / 2, getHeight() / 2);

4 circle.setColor(Color.blue);

5 }

But when we run this code, we don’t see the circle. What is missing from our start function?

• We never set the circle’s radius.We need to add the linecircle.setRadius(40);After line 4

• We are setting the position of the ball to be off the canvas.

  We need to change line 3 to be

  circle.setPosition(0, 0);

• We are creating the circle incorrectly. We need to specify the width and height.

  We need to change line 2 to be

  var circle = new Circle(40, 40);

• We create the circle and position it correctly on the screen, but we never add it to the screen.

  We need to add the line

  add(circle);

  after line 4

What is the output of the following program: (Assume the user enters ‘Florence’ then ‘Fernandez’.)

var first_name = readLine("What is your first name? ");

var last_name = readLine("What is your last name? ");

var whole_name = first_name + last_name;

println (whole_name);

• Fernandez Florence

• Florence

  Fernandez

• FlorenceFernandez

• Florence Fernandez

Which of the following choices is a properly formed JavaScript variable name, meaning it is both legal in the JavaScript language and considered good style?

• user_age

• UserAge

• userAge

• User age

If you wanted to use the following code to draw a circle to the canvas with the radius, and x and y coordinates given by the user, how would you ask for this information?

var circle = new Circle(radius);

circle.setPosition(x, y);

circle.setColor(color);

add(circle);

• var x = readLine(“What is the x coordinate? “);

  var y = readLine(“What is the y coordinate? “);

  var radius = readLine(“What is the radius of the circle? “);

• var x = readInt(“What is the x coordinate? “);

  var y = readInt(“What is the y coordinate? “);

  var radius = readInt(“What is the radius of the circle? “);

• var x = readLine(“What is the x coordinate? “);

  var y = readLine(“What is the y coordinate? “);

  var radius = readInt(“What is the radius of the circle? “);

• var x = readInt(“What is the x coordinate? “);

  var y = readInt(“What is the y coordinate? “);

  var radius = readLine(“What is the radius of the circle? “);