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
var a = 5, b = 10, c = "5";
var x = a;

a == c; // returns true

a === c; // returns false

a == x; // returns true

a != b; // returns true

a > b; // returns false

a < b; // returns true

a >= b; // returns true

a <= b; // returns true

a >= c; // returns true

a <= c; // returns true

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, z = 15;

x = y; //x would be 10

x += 1; //x would be 6

x -= 1; //x would be 4

x *= 5; //x would be 25

x /= 5; //x would be 1

x %= 2; //x would be 1

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.