JavaScript Operators

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Javascript Operators:

JavaScript includes operators as in other languages. An operator performs some operation on single or multiple operands (data value) and produces a result. For example 1 + 2, where + sign is an operator and 1 is left operand and 2 is right operand. + operator adds two numeric values and produces a result which is 3 in this case.

Syntax:

<Left operand> operator <right operand>

<Left operand> operator

JavaScript includes following categories of operators.

  1. Arithmetic Operators
  2. Comparison Operators
  3. Logical Operators
  4. Assignment Operators
  5. Conditional Operators

Arithmetic Operators:

Arithmetic operators are used to perform mathematical operations between numeric operands.

Operator Description
+ Adds two numeric operands.
- Subtract right operand from left operand
* Multiply two numeric operands.
/ Divide left operand by right operand.
% Modulus operator. Returns remainder of two operands.
++ Increment operator. Increase operand value by one.
-- Decrement operator. Decrease value by one.

The following example demonstrates how arithmetic operators perform different tasks on operands.

Example: Arithmetic Operator

var x = 5, y = 10, z = 15;

x + y; //returns 15

y - x; //returns 5

x * y; //returns 50

y / x; //returns 2

x % 2; //returns 1

x++; //returns 6

x--; //returns 4

+ operator performs concatenation operation when one of the operands is of string type.

The following example shows how + operator performs operation on operands of different data types.

Example: + operator

var a = 5, b = "Hello ", c = "World!", d = 10;

a + b; // "5Hello "

b + c; // "Hello World!"

a + d; // 15

 

Comparison Operators:

JavaScript language includes operators that compare two operands and return Boolean value true or false.

Operators Description
== Compares the equality of two operands without considering type.
=== Compares equality of two operands with type.
!= Compares inequality of two operands.
> Checks whether left side value is greater than right side value. If yes then returns true otherwise false.
< Checks whether left operand is less than right operand. If yes then returns true otherwise false.
>= Checks whether left operand is greater than or equal to right operand. If yes then returns true otherwise false.
<= Checks whether left operand is less than or equal to right operand. If yes then returns true otherwise false.

The following example demonstrates how comparison operators perform different tasks.

Example: Comparison Operators

Logical Operators:

Logical operators are used to combine two or more conditions. JavaScript includes following logical operators.

Operator Description
&& && is known as AND operator. It checks whether two operands are non-zero (0, false, undefined, null or "" are considered as zero), if yes then returns 1 otherwise 0.
|| || is known as OR operator. It checks whether any one of the two operands is non-zero (0, false, undefined, null or "" is considered as zero).
!

! is known as NOT operator. It reverses the boolean result of the operand (or condition)

Example: Logical Operators

var a = 5, b = 10;

(a != b) && (a < b); // returns true

(a > b) || (a == b); // returns false

(a < b) || (a == b); // returns true

!(a < b); // returns false

!(a > b); // returns true

Assignment Operators:

JavaScript includes assignment operators to assign values to variables with less key strokes.

Assignment operators Description
= Assigns right operand value to left operand.
+= Sums up left and right operand values and assign the result to the left operand.
-= Subtract right operand value from left operand value and assign the result to the left operand.
*= Multiply left and right operand values and assign the result to the left operand.
/= Divide left operand value by right operand value and assign the result to the left operand.
%= Get the modulus of left operand divide by right operand and assign resulted modulus to the left operand.

Example: Assignment operators

var x = 5, y = 10;

x = y; //x would be 10

x += 1; //x would be 11

x -= 1; //x would be 10

x *= 5; //x would be 50

x /= 5; //x would be 10

x %= 2; //x would be 

Ternary Operator:

JavaScript includes special operator called ternary operator :? that assigns a value to a variable based on some condition. This is like short form of if-else condition.

Syntax:

<condition> ? <value1> : <value2>;

Ternary operator starts with conditional expression followed by ? operator. Second part ( after ? and before : operator) will be executed if condition turns out to be true. If condition becomes false then third part (after :) will be executed.

Example: Ternary operator

var a = 10, b = 5;

var c = a > b? a : b; // value of c would be 10
var d = a > b? b : a; // value of d would be 5

Points to Remember :

  1. JavaScript includes operators that perform some operation on single or multiple operands (data value) and produce a result.
  2. JavaScript includes various categories of operators: Arithmetic operators, Comparison operators, Logical operators, Assignment operators, Conditional operators.
  3. Ternary operator ?: is a conditional operator.