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.
- Arithmetic Operators
- Comparison Operators
- Logical Operators
- Assignment Operators
- 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;
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 0
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 :
- JavaScript includes operators that perform some operation on single or multiple operands (data value) and produce a result.
- JavaScript includes various categories of operators: Arithmetic operators, Comparison operators, Logical operators, Assignment operators, Conditional operators.
- Ternary operator ?: is a conditional operator.
