What Are Operators?

Operators perform actions on values.

Examples:

• Addition

• Comparison

• Checking conditions

• Assigning values

Arithmetic Operators

Used for mathematical calculations.

Arithmetic Operators Table

Addition

const a = 10;
const b = 5;

console.log(a + b);

Output

15

Subtraction

console.log(10 - 5);

Output

5

Multiplication

console.log(4 * 3);

Output

12

Division

console.log(20 / 4);

Output

5

Modulus %

Returns remainder.

console.log(10 % 3);

Output

1

Comparison Operators

Used to compare values.

Result is always:

true or false

Comparison Operators Table

Equal ==

Checks value only.

console.log(5 == "5");

Output

true

JavaScript converts types automatically.

Strict Equal ===

Checks:

• Value

• Data type

console.log(5 === "5");

Output

false

== vs ===

Recommendation

Prefer:

===

because it avoids unexpected type conversion.

Not Equal !=

console.log(10 != 5);

Output

true

Greater Than and Less Than

console.log(10 > 5);

console.log(3 < 8);

Output

true
true

Logical Operators

Used to combine conditions.

Logical Operators Table

AND Operator &&

Returns true only if both conditions are true.

const age = 20;
const hasID = true;

console.log(age >= 18 && hasID);

Output

true

OR Operator ||

Returns true if at least one condition is true.

console.log(true || false);

Output

true

NOT Operator !

Reverses boolean value.

console.log(!true);

Output

false

Truth Table for Logical Operators

Assignment Operators

Used to assign or update values.

Assignment Operators Table

Basic Assignment

let score = 10;

Add and Assign +=

let score = 10;

score += 5;

console.log(score);

Output

15

Subtract and Assign -=

let score = 20;

score -= 5;

console.log(score);

Output

15

Operator Categories Diagram

Practical Example

const age = 20;
const isStudent = true;

if (age >= 18 && isStudent) {
  console.log("Eligible");
}

Output

Eligible

Assignment

1. Arithmetic Operations

const a = 10;
const b = 5;

console.log(a + b);
console.log(a - b);
console.log(a * b);
console.log(a / b);
console.log(a % b);

2. Compare Values

console.log(5 == "5");

console.log(5 === "5");

3. Logical Condition

const age = 22;
const hasLicense = true;

console.log(age >= 18 && hasLicense);

Common Beginner Mistakes

Using == Accidentally

5 == "5"

returns:

true

Use === for safer comparisons.

Confusing % With Percentage

10 % 3

means remainder, not percentage.

Key Takeaways

Final Notes

Operators are used everywhere in JavaScript:

• Conditions

• Calculations

• Authentication

• Loops

• APIs

• Form validation

Mastering operators is important before learning:

• Functions

• Loops

• Objects

• Backend logic