JS Functions & Parameters Review

Why do we write functions?

• Make our code easier to understand by giving a readable name to a group of instructions

• Avoid writing repeated code

• Make our code reusable

• All of the above

In the following function printThreeTimes:

function printThreeTimes(word){

println(word);

println(word);

println(word);

}

What is the parameter of the function?

• printThreeTimes

• function

• println

• word

What is the output of the following program?

function start(){

var x=5;

sumTo(x);

println(x);

}

function sumTo(num){

var sum=0;

for(var i=0; i<=num; i++){

sum +=i;

}

println(sum);

}

• 5

  15

• 15

  5

• 5

• 15

• none - there is a syntax error

What is printed by the following program?

function printNumbers(two, one, zero) {

println(two);

println(one);

println(zero);

}

function start(){

var zero=0;

var one =1;

var two=2;

printNumbers(zero, one, two);

}

• 2

  1

  0

• 0

  1

  2

• zero

  one

  two

• two

  one

  zero

How many parameters go into the function sum, and how many return values come out of the function sum?

function sum(first, second, third){

var result=first+second+third;

println(first);

println(second);

println(third);

return result;

}

• 3 parameters go in, 1 return value comes out

• 3 parameters go in, 3 return values come out

• 1 parameter goes in, 4 return values come out

• 1 parameter goes in, 1 return value comes out

We want to write a function isSuperman that takes in two parameters isBird and isPlane and returns true if it is in fact Superman and false otherwise. If it's not a bird and it's not a plane, it must be Superman. Which of the following functions is the correct implementation of isSuperman?

• function isSuperman(isBird, isPlane){

  return isBird || isPlane?}

• function isSuperman(isBird, isPlane){

  return !isBird || !isPlane;}

• function isSuperman(isBird, isPlane){

  return !isBird && !isPlane;}

• function isSuperman(isBird, isPlane){

  return isBird && isPlane;}

In the following code:

function start(){

var length=5;

var width=4;

rectangleArea(length, width);}

/*This function prints out the area of a triangle given its base and height */

function rectangleArea(base, height){

var area=base * height;

println(area);}

What are the names of the parameters?

• length and width

• length and height

• base and height

• base and width

What is printed by the following program?

function product (x, y){

return x * y; }

function difference (x, y){

return x-y; }

function start (){

var x=2;

var y=5;

var value1=product (x,y);

var value2=difference (y, x);

var result = difference (value1, value2);

println(result);}

• 7

• -7

• 13

• -13

In the following code:

function drawCircle(radius, x=getWidth()/2, y=getHeight()/2, color=Color.red){

var circle - new Circle(radius);

circle.setPosition(x, y);

circle.setColor(color);

add(circle);}

What is the minimum number of parameters that must be given when calling the 'drawCircle' function?

• One

• Two

• Three

• Four

What will be printed to the screen when the following program is run?

function start(){

println(doubleNumber(doubleNumber(10)));}

function doubleNumber(x){

var doubledX = 2*x;

return doubledX;}

• 10

• 20

• 40

• 100