JavaScript Operators

Operators in JavaScript are special symbols used to perform operations on values. They can be used for arithmetic calculations, comparisons, logical operations, etc. Here are some of the most common types of operators in JavaScript:

1. Arithmetic Operators
2. Comparison Operators
3. Logical Operators
4. Assignment Operators (covered later)
5. String Operators

Arithmetic Operators

Arithmetic operators are used to perform mathematical operations.

Addition (+): Adds two numbers.

5 + 3  // 8

Subtraction (-): Subtracts the second number from the first.

9 - 4  // 5

Multiplication (*): Multiplies two numbers.

6 * 7  // 42

Division (/): Divides the first number by the second.

8 / 2  // 4

Modulus (%): Returns the remainder of a division.

10 % 3  // 1

Comparison Operators

Comparison operators are used to compare two values and return a boolean (true or false).

Equal (==): Checks if two values are equal.

5 == 5  // true
5 == '5'  // true

Strict Equal (===): Checks if two values are equal and of the same type.

5 === 5  // true
5 === “5"  // false

Notice, this time, the string ”5" is not equal to 5. Strict operators don’t try to match the data and expect them to be precisely the same.

Not Equal (!=): Checks if two values are not equal.

5 != 3  // true
5 != '5'  // false

Strict Not Equal (!==): Checks if two values are not equal or not of the same type.

5 !== 5  // false
5 !== '5'  // true

Greater Than (>): Checks if the first value is greater than the second.

7 > 5  // true

Less Than (<): Checks if the first value is less than the second.

3 < 4  // true

Greater Than or Equal (>=): Checks if the first value is greater than or equal to the second.

7 >= 7  // true
7 >= 5  // true

Less Than or Equal (<=): Checks if the first value is less than or equal to the second.

5 <= 5  // true
3 <= 4  // true

Logical Operators

Logical operators are used to combine multiple boolean expressions or values and return a boolean result.

AND (&&): Returns true if both expressions are true.

true && true  // true
true && false  // false

OR (||): Returns true if at least one expression is true.

true || false  // true
false || false  // false

NOT (!): Inverts the value of a boolean expression.

!true  // false
!false  // true

String Operators

Strings can be concatenated (joined together) using the addition (+) operator.

Concatenation (+): Joins two or more strings together.

'Hello, ' + 'World!'  // 'Hello, World!'

Exercise

Here are some examples of using these operators. Run each one in the browser, but try to guess the output before you run it:

Arithmetic Operations:

2 + 3
10 - 7
4 * 5 
20 / 4 
15 % 4 

Comparison Operations:

5 == '5' 
5 === '5' 
10 != 8 
6 !== '6' 
9 > 3  
7 < 10 
8 >= 8
4 <= 5 

Logical Operations:

true && false 
true || false 
!true 

String Concatenation:

'JavaScript ' + 'is fun!' 

I’ll leave the answers below if you want to confirm your suspicions.

Operators are essential for performing various operations on values and controlling the flow of your programs. They are fundamental tools for writing logical and functional code in JavaScript and nearly every programming language.

Next, we will explore expressions in JavaScript, which combine values and operators to produce a new value.

Answers to above exercise

Arithmetic Operations:

2 + 3  // 5
10 - 7  // 3
4 * 5  // 20
20 / 4  // 5
15 % 4  // 3

Comparison Operations:

5 == '5'  // true
5 === '5'  // false
10 != 8  // true
6 !== '6'  // true
9 > 3  // true
7 < 10  // true
8 >= 8  // true
4 <= 5  // true

Logical Operations:

true && false  // false
true || false  // true
!true  // false

String Concatenation:

'JavaScript ' + 'is fun!'  // 'JavaScript is fun!'