JavaScript Arithmetic

A typical thing to do with numbers is arithmetic.

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JavaScript Arithmetic Operators

Arithmetic operators perform arithmetic on numbers (literals or variables).

Operator	Description
+	Addition
-	Subtraction
*	Multiplication
/	Division
%	Modulus
++	Increment
--	Decrement

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Arithmetic Operations

A typical arithmetic operation operates on two numbers.
The two numbers can be literals:

Example

var x = 100 + 50; 

 

or variables:

Example

var x = a + b; 

 

or expressions:

Example

var x = (100 + 50) * a; 

 

Operators and Operands

The numbers (in an arithmetic operation) are called operands.
The operation (to be performed between the two operands) is defined by an operator.

Operand	Operator	Operand
100	+	50

The addition operator (+) adds numbers:

Adding

var x = 5;
var y = 2;
var z = x + y;

  

The subtraction operator (-) subtracts numbers.

Subtracting

var x = 5;
var y = 2;
var z = x - y; 

 

The multiplication operator (*) multiplies numbers.

Multiplying

var x = 5;
var y = 2;
var z = x * y; 

 

The division operator (/) divides numbers.

Dividing

var x = 5;
var y = 2;
var z = x / y; 

 

The modular operator (%) returns the division remainder.

Modulus

var x = 5;
var y = 2;
var z = x % y; 

 

The increment operator (++) increments numbers.

Incrementing

var x = 5;
x++;
var z = x;

 

The decrement operator (--) decrements numbers.

Decrementing

var x = 5;
x--;
var z = x;

  

Operator Precedence

Operator precedence describes the order in which operations are performed in an arithmetic expression.

Example

var x = 100 + 50 * 3; 

 

Is the result of example above the same as 150 * 3, or is it the same as 100 + 150?
Is the addition or the multiplication done first?
As in traditional school mathematics, the multiplication is done first.
Multiplication (*) and division (/) have higher precedence than addition (+) and subraction (-).
And (as in school mathematics) the precedence can be changed by using parentheses:

Example

var x = (100 + 50) * 3; 

 

When using parentheses, the operations inside the parentheses are computed first.
When many operations have the same precedence (like addition and subtraction), they are computed from left to right:

Example

var x = 100 + 50 - 3; 

 

Arithmetic Operator Precedence

The following table lists JavaScript arithmetic operators, ordered from highest to lowest precedence:

Operator	Precedence
( )	Expression grouping
++ --	Increment and decrement
* / %	Multiplication, division, and modulo division
+ -	Addition and subtraction