JavaScript Operators

When writing a program, we don't just store values—we also need to perform operations on those values.

For example, we may want to add two numbers, compare two values, check whether something is true, or assign a new value to a variable.

JavaScript provides operators for performing these tasks.

What is an Operator?

An operator is a symbol or keyword that tells JavaScript to perform a specific operation on one or more values.

For example:

let result = 10 + 5;

Here:

• 10 and 5 are operands.

• + is the operator.

• result stores the final value.

The output is:

15

Types of JavaScript Operators

JavaScript has several types of operators:

Let's understand the most important ones.

1. Arithmetic Operators

Arithmetic operators are used for mathematical calculations.

Example

let a = 10;
let b = 3;

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

Output:

13
7
30
3.3333333333333335
1
1000

The % operator gives the remainder after division.

For example:

console.log(10 % 3);

Output:

1

because 10 divided by 3 leaves a remainder of 1.

2. Assignment Operators

Assignment operators are used to assign values to variables.

The basic assignment operator is:

=

Example:

let age = 20;

Here, 20 is assigned to age.

JavaScript also provides shorthand assignment operators.

For example:

let score = 50;

score += 10;

console.log(score);

Output:

60

score += 10 is simply a shorter way of writing:

score = score + 10;

3. Comparison Operators

Comparison operators are used to compare two values.

They return either:

true

or:

false

For example:

let age = 20;

console.log(age > 18);
console.log(age < 18);
console.log(age === 20);

Output:

true
false
true

== vs ===

This is particularly important in JavaScript.

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

Output:

true

But:

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

Output:

false

== allows type coercion, while === checks both value and type.

As a general rule, prefer === and !== in modern JavaScript unless you have a specific reason to use loose equality.

4. Logical Operators

Logical operators are used to combine or reverse conditions.

There are three main logical operators:

AND (&&)

let age = 25;
let hasLicense = true;

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

Output:

true

Both conditions are true.

OR (||)

let isWeekend = false;
let isHoliday = true;

console.log(isWeekend || isHoliday);

Output:

true

At least one condition is true.

NOT (!)

let isLoggedIn = true;

console.log(!isLoggedIn);

Output:

false

The ! operator reverses the Boolean value.

These operators become especially useful when we learn conditional statements.

5. Increment and Decrement Operators

Sometimes we simply want to increase or decrease a number by 1.

For this, JavaScript provides:

++  → Increase by 1
--  → Decrease by 1

Example:

let count = 5;

count++;

console.log(count);

Output:

6

Similarly:

let count = 5;

count--;

console.log(count);

Output:

4

You'll commonly see these operators when working with loops.

6. Ternary Operator

The ternary operator is a short way of writing a simple condition.

Its syntax is:

condition ? valueIfTrue : valueIfFalse;

For example:

let age = 20;

let result = age >= 18 ? "Adult" : "Minor";

console.log(result);

Output:

Adult

It's basically a shorter version of an if...else statement.

We'll learn this properly when we cover conditional statements.

7. String Operators

The + operator can also be used to join strings.

let firstName = "John";
let lastName = "Smith";

let fullName = firstName + " " + lastName;

console.log(fullName);

Output:

John Smith

This is called string concatenation.

JavaScript also provides template literals, which are often cleaner for combining strings:

let name = "John";
let age = 21;

console.log(`My name is ${name} and I am ${age} years old.`);

Output:

My name is John and I am 21 years old.

8. Nullish Coalescing Operator

The ?? operator is used when we want to provide a default value if something is null or undefined.

let username = null;

let name = username ?? "Guest";

console.log(name);

Output:

Guest

Here, because username is null, JavaScript uses "Guest" instead.

This operator is especially useful when handling optional data.

Operator Precedence

Just like mathematics, JavaScript follows certain rules when multiple operators are used in an expression.

For example:

let result = 10 + 5 * 2;

console.log(result);

The result is:

20

not 30, because multiplication happens before addition.

You can use parentheses when you want to make the order clear:

let result = (10 + 5) * 2;

console.log(result);

Output:

30

Using parentheses is often a good idea when an expression could become confusing.

A Practical Example

Let's combine several operators:

let price = 100;
let quantity = 3;

let total = price * quantity;

let discount = total >= 300 ? 20 : 0;

let finalPrice = total - discount;

console.log(finalPrice);

Output:

280

Here we're using:

• * for multiplication

• >= for comparison

• ? : for the ternary operator

• - for subtraction

• = for assignment

This is how operators come together in real programs.

Conclusion

Operators are the tools JavaScript gives us to perform calculations, compare values, assign data, and make decisions.

The most important ones to remember initially are:

Arithmetic     → +  -  *  /  %
Assignment     → =  +=  -=  *=
Comparison     → ===  !==  >  <  >=  <=
Logical        → &&  ||  !
Increment      → ++
Decrement      → --
Ternary        → ? :

Once you understand operators, you're ready to start using them to make decisions in your programs with conditional statements.