Computer processors can perform more than just arithmetic
calculations. They can also make decisions based on certain
conditions.
This ability to make decisions allows programs to handle different
outcomes.
Application Logic Samples
What possible outcomes may occur when I type in my age?
Application Logic Samples
What possible outcomes may occur when I try to login?
Application Logic Samples
How does the game know when to finish the round or match?
The Boolean Data Type
the boolean data type is used to store values that can be either true
or false. It is used for logical expressions, which are questions or
conditions that the computer can evaluate.
1
let isRaining =true;
2
let hasUmbrella =false;
Boolean Logic
The study of how logical expressions are formed and evaluated is
called boolean logic.
In programming, these logical expressions are constructed using
operators and values, and they always result in either true or
false.
Boolean Logic Operators
Comparison Operators
Operator
Name
Description
==
Equality
Returns true if operands are equal.
!=
Inequality
Returns true if operands are not equal.
>
Greater Than
Returns true if left operand is greater than right.
Boolean Logic Operators
Comparison Operators
Operator
Name
Description
<
Less Than
Returns true if left operand is less than right.
>=
Greater Than or Equal
Returns true if left operand is greater than or equal to right.
<=
Less Than or Equal
Returns true if left operand is less than or equal to right.
Boolean Logic Operators
Logical Operators
Operator
Name
Description
&&
Logical AND
Returns true if both operands are true.
||
Logical OR
Returns true if at least one operand is true.
!
Logical NOT
Returns true if the operand is false, and vice versa.
Sample Boolean Expressions
'abc' == 'abc'
'ABC' == 'abc'
100 != 99
'ABC' != 'abc'
100 > 100
100 >= 100
Sample Boolean Expressions
!true
!true == false
!(100 > 100)
Boolean Variables
Boolean values and expressions can be saved to a variable.
1
let health =100;
2
let isAlive = health >0;
Key Terms
Boolean
A data type that can only have one of two possible values: true
or false. It is fundamental to computer logic, as it represents
the outcome of a logical question or condition.
Logical Expression
A statement that a computer can evaluate to determine if it is
true or false.
'F' → Fullscreen
Objectives
Evaluating boolean expressions
Saving boolean expression results to variables
Activity Tasks
Create a new project named 2-1-boolean-logic.js.
Complete each task individually.
Task 1: Boolean Variables
and Name Checks
Evaluate boolean expressions and save the results to variables.
2-1-boolean-logic.js
1
// Initialize variables
2
let name ="Mr. Mortimer";
3
let age =30;
4
let balance =150.00;
5
let isTeacher =true;
6
let isMillionaire =false;
7
8
// Boolean expressions
9
let nameIsMortimer = name =="Mr. Mortimer";
10
let canDrive = age >=16;
11
let canBuyCar = balance >31000;
12
let isSenior = age >=65;
13
//
Task 2: Name Checks
Output the results of boolean expressions.
2-1-boolean-logic.js
1
// Initialize variables
2
let name ="Mr. Mortimer";
3
let age =30;
4
let balance =150.00;
5
let isTeacher =true;
6
let isMillionaire =false;
7
8
// Boolean expressions
9
let nameIsMortimer = name =="Mr. Mortimer";
10
let canDrive = age >=16;
11
let canBuyCar = balance >31000;
12
let isSenior = age >=65;
13
14
console.log("-Name Checks-");
15
console.log(`Is my name Mr. Mortimer? ${nameIsMortimer}`);
16
console.log(`Is my name Mr. Mertens? ${name =="Mr. Mertens"}`);
17
console.log(`My name is not Mr. Merriman: ${name !="Mr. Merriman"}`);
18
alert("Press enter to continue...")
19
//
Task 3: Age-Related Checks
2-1-boolean-logic.js
1
// Initialize variables
2
let name ="Mr. Mortimer";
3
let age =30;
4
let balance =150.00;
5
let isTeacher =true;
6
let isMillionaire =false;
7
8
// Boolean expressions
9
let nameIsMortimer = name =="Mr. Mortimer";
10
let canDrive = age >=16;
11
let canBuyCar = balance >31000;
12
let isSenior = age >=65;
13
14
console.log("-Name Checks-");
15
console.log(`Is my name Mr. Mortimer? ${nameIsMortimer}`);
16
console.log(`Is my name Mr. Mertens? ${name =="Mr. Mertens"}`);
17
console.log(`My name is not Mr. Merriman: ${name !="Mr. Merriman"}`);
18
alert("Press enter to continue...")
19
20
console.log("\n-Age-Related Checks-");
21
console.log(`Am I old enough to drive? ${canDrive}`);
22
let canRentCar = age >=25;
23
console.log(`Am I old enough to rent a car? ${canRentCar}`);
24
console.log(`Am I eligible for a senior citizen discount? ${isSenior}`);
25
alert("Press enter to continue...")
26
//
Task 4: Monetary Checks
2-1-boolean-logic.js
1
// Initialize variables
2
let name ="Mr. Mortimer";
3
let age =30;
4
let balance =150.00;
5
let isTeacher =true;
6
let isMillionaire =false;
7
8
// Boolean expressions
9
let nameIsMortimer = name =="Mr. Mortimer";
10
let canDrive = age >=16;
11
let canBuyCar = balance >31000;
12
let isSenior = age >=65;
13
14
console.log("-Name Checks-");
15
console.log(`Is my name Mr. Mortimer? ${nameIsMortimer}`);
16
console.log(`Is my name Mr. Mertens? ${name =="Mr. Mertens"}`);
17
console.log(`My name is not Mr. Merriman: ${name !="Mr. Merriman"}`);
18
alert("Press enter to continue...")
19
20
console.log("\n-Age-Related Checks-");
21
console.log(`Am I old enough to drive? ${canDrive}`);
22
let canRentCar = age >=25;
23
console.log(`Am I old enough to rent a car? ${canRentCar}`);
24
console.log(`Am I eligible for a senior citizen discount? ${isSenior}`);
25
alert("Press enter to continue...")
26
27
console.log("\n-Bank Account Checks-");
28
console.log(`Do I have enough to buy a Dodge Challenger? ${canBuyCar}`);
29
let hasFunds = balance >0;
30
console.log(`Do I have a positive bank balance? ${hasFunds}`);
31
alert("Press enter to continue...")
32
//
Task 5: Logical Not
Operations
2-1-boolean-logic.js
1
// Initialize variables
2
let name ="Mr. Mortimer";
3
let age =30;
4
let balance =150.00;
5
let isTeacher =true;
6
let isMillionaire =false;
7
8
// Boolean expressions
9
let nameIsMortimer = name =="Mr. Mortimer";
10
let canDrive = age >=16;
11
let canBuyCar = balance >31000;
12
let isSenior = age >=65;
13
14
console.log("-Name Checks-");
15
console.log(`Is my name Mr. Mortimer? ${nameIsMortimer}`);
16
console.log(`Is my name Mr. Mertens? ${name =="Mr. Mertens"}`);
17
console.log(`My name is not Mr. Merriman: ${name !="Mr. Merriman"}`);
18
alert("Press enter to continue...")
19
20
console.log("\n-Age-Related Checks-");
21
console.log(`Am I old enough to drive? ${canDrive}`);
22
let canRentCar = age >=25;
23
console.log(`Am I old enough to rent a car? ${canRentCar}`);
24
console.log(`Am I eligible for a senior citizen discount? ${isSenior}`);
25
alert("Press enter to continue...")
26
27
console.log("\n-Bank Account Checks-");
28
console.log(`Do I have enough to buy a Dodge Challenger? ${canBuyCar}`);
29
let hasFunds = balance >0;
30
console.log(`Do I have a positive bank balance? ${hasFunds}`);
31
alert("Press enter to continue...")
32
33
console.log("\n-Boolean Checks-");
34
console.log(`${name} is a teacher: ${isTeacher}`);
35
console.log(`${name} is a millionaire: ${isMillionaire}`);
36
let notMillionaire =!isMillionaire;
37
console.log(`So, ${name} isn't a millionaire? ${notMillionaire}`);
38
alert("Press enter to continue...")
39
//
Task 6: Logical AND & OR
2-1-boolean-logic.js
1
// Initialize variables
2
let name ="Mr. Mortimer";
3
let age =30;
4
let balance =150.00;
5
let isTeacher =true;
6
let isMillionaire =false;
7
8
// Boolean expressions
9
let nameIsMortimer = name =="Mr. Mortimer";
10
let canDrive = age >=16;
11
let canBuyCar = balance >31000;
12
let isSenior = age >=65;
13
14
console.log("-Name Checks-");
15
console.log(`Is my name Mr. Mortimer? ${nameIsMortimer}`);
16
console.log(`Is my name Mr. Mertens? ${name =="Mr. Mertens"}`);
17
console.log(`My name is not Mr. Merriman: ${name !="Mr. Merriman"}`);
18
alert("Press enter to continue...")
19
20
console.log("\n-Age-Related Checks-");
21
console.log(`Am I old enough to drive? ${canDrive}`);
22
let canRentCar = age >=25;
23
console.log(`Am I old enough to rent a car? ${canRentCar}`);
24
console.log(`Am I eligible for a senior citizen discount? ${isSenior}`);
25
alert("Press enter to continue...")
26
27
console.log("\n-Bank Account Checks-");
28
console.log(`Do I have enough to buy a Dodge Challenger? ${canBuyCar}`);
29
let hasFunds = balance >0;
30
console.log(`Do I have a positive bank balance? ${hasFunds}`);
31
alert("Press enter to continue...")
32
33
console.log("\n-Boolean Checks-");
34
console.log(`${name} is a teacher: ${isTeacher}`);
35
console.log(`${name} is a millionaire: ${isMillionaire}`);
36
let notMillionaire =!isMillionaire;
37
console.log(`So, ${name} isn't a millionaire? ${notMillionaire}`);
38
alert("Press enter to continue...")
39
40
console.log("\n-Logical Operator Examples-");
41
let canDriveAndBuy = canDrive && canBuyCar;
42
console.log(`Am I old enough to drive AND have enough to buy a Dodge Challenger? ${canDriveAndBuy}`);
43
let canDriveOrBuy = canDrive || canBuyCar;
44
console.log(`Am I old enough to drive OR have enough to buy a Dodge Challenger? ${canDriveOrBuy}`);
45
//
Sample Output
Your program output should something similar to the sample output
below.
Sample Output
-Name Checks-
Is my name Mr. Mortimer? true
Is my name Mr. Mertens? false
My name is not Mr. Merriman: true
Press enter to continue... [Enter]
-Age-Related Checks-
Am I old enough to drive? true
Am I old enough to rent a car? true
Am I eligible for a senior citizen discount? false
Press enter to continue... [Enter]
-Bank Account Checks-
Do I have enough to buy a Dodge Challenger? false
Do I have a positive bank balance? true
Press enter to continue... [Enter]
-Boolean Checks-
Mr. Mortimer is a teacher: true
Mr. Mortimer is a millionaire: false
So, Mr. Mortimer isn't a millionaire? true
Press enter to continue... [Enter]
-Logical Operator Examples-
Am I old enough to drive AND have enough to buy a Dodge Challenger? false
Am I old enough to drive OR have enough to buy a Dodge Challenger? true
Reflection Questions
You may write your reflection answers as comments at the bottom of
your code.
How do boolean expressions and logical operators connect to
real-world decision-making processes, like the examples of age
verification or logging in? Think about how they help a program
"decide" what to do.
The activity uses different types of operators (comparison and
logical). Describe a scenario where you would need to use a
combination of comparison operators and a logical operator (&& or
||) to get the correct result. For example, checking if a person
is both old enough to drive AND has enough money to buy a car.
Submission
Submit your activity and reflection answers to the appropriate
dropbox.
Evaluating boolean expressions 
Create a new project named 2-1-boolean-logic.js.