Creating Reusable Code with Functions

Question 1

How would you “call a function” named sayHello?

Answer 1

Type the name of the function followed by parentheses: sayHello();

Question 2

What describes a function?

Answer 2

A function lets you store a block of code that you can use over and over again.

Question 3

• Create a function named sayHi.
• Inside the sayHi() function add the code to make an alert appear with the word “Hi” in it. The alert command should go inside the function’s code block.
• Call the new sayHi function you just created.

Answer 3

function sayHi() {
  alert("Hi");
}

sayHi();

Question 4

T/F: A JavaScript function can return several values at once. For example:

function myFunction() {

return ‘Mon’, ‘Tues’, ‘Wed’, ‘Thurs’, ‘Fri’;

}

var days = myFunction();

Answer 4

False

Question 5

After the code below runs, what value is stored in the variable dayOfWeek:

function getDay() {

return “Monday”; alert(“Calculating day”);

return “Friday”;

}

var dayOfWeek = getDay();

Answer 5

“Monday”

Question 6

What JavaScript keyword is used to send back a value from a function?

Answer 6

return

Question 7

T/F: You can have more than one return statement in a function.

Answer 7

True

Question 8

What does the JavaScript return statement do?

Answer 8

return exits a function and sends a value back to the spot in the program where the function was called

Question 9

• Create a function named getYear
• Inside the function’s code block add this line of code

var year = new Date().getFullYear();

This creates a new variable and stores the current year in it. Now, add a statement that returns this variable from the function.

• Call the getYear function: store the returned value of the function in a new variable namedyearToday.

Answer 9

function getYear() {
  var year = new Date().getFullYear();
  return year;
}

var yearToday = getYear();

Question 10

When talking about JavaScript functions, what is an “argument”?

Answer 10

A value that you pass to a function when you call the function.

Question 11

Complete the code below to call the function and pass the value 12 to it:

function getRandom( upper ) {

return Math.floor(Math.random() * upper) + 1;

} ;

_____;

Answer 11

getRandom(12);

Question 12

When talking about JavaScript functions, what is a “parameter”?

Answer 12

A variable in which the function stores information passed to it.

Question 13

T/F: You can pass as many arguments to a function as you’d like.

Answer 13

True

Question 14

• Here’s a simple challenge: create a function named returnValue() that accepts a single argument, then returns that argument. This isn’t a useful function, but we want to make sure you know how to create a function that can accept information when it is called.
• Now that you’ve created the returnValue function, call it, by passing it a literal string value – a series of characters in quote marks like this: ‘My argument’. Store the results of the function in a variable named echo.

Answer 14

function returnValue(arg) {
  return arg;
}

var echo = returnValue(“My argument”);

Question 15

• Create a new function named max() which accepts two numbers as arguments. The function should return the larger of the two numbers. You’ll need to use a conditional statement to test the 2 numbers to see which is the larger of the two.
• Call the function and display the results in an alert dialog. You can pass the results of a function directly to the alert() method.

Answer 15

function max(num1, num2) {
  if (num1 \> num2) {
    return num1;
  } else {
    return num2;
  }
}

alert(max(1, 2));

Question 16

Given the code below, what appears in the alert dialogue when this program runs?

var message = “Welcome!”;

function setMessage() {

message = “Go away!”;

}

setMessage();

alert(message);

Answer 16

“Go away!”

Question 17

Given the code below, what appears in the alert dialogue when this program runs?

var name = “Trish”;

function setName() {

var name = “Sarah”;

}

setName();

alert(name);

Answer 17

“Trish”

Question 18

What is “global scope”?

Answer 18

When a variable is accessible anywhere inside a program – in the body of the program and within functions.

Question 19

T/F: When you declare a variable within a function, that variable is only accessible within that function.

Answer 19

True

Question 20

Finish the code below so that the variable counter inside the function is only accessible inside that function:

var counter = 0;

function doStuff( ) {

_____ counter = 10;

}

Answer 20

var

Question 21

Given this function, write the code to call it:

function warning() {

alert(‘Warning, warning, warning!’);

}

_____;

Answer 21

warning()

Question 22

Finish the code below, so that the function returns the message variable:

function greeting( name ) {

var message = “Hello “ + name;

_____;

}

Answer 22

return message

Question 23

When you call an function, you can pass that function one or more _____.

Answer 23

arguments

Question 24

What is “scope” in JavaScript?

Answer 24

Scope is the context in which a variable can be accessed, such as within a function, or within the global scope of the entire program.

Question 25

How do programmers describe the act of running the programming within a function?

Answer 25

To “call” a function