JavaScript Arithmetic Operators

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

Arithmetic Operations

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

let x = 100 + 50;

or variables:

let x = a + b;

or expressions:

let 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.

Adding

The addition operator (+) adds numbers:

let x = 5;
let y = 2;
let z = x + y;

Subtracting

The subtraction operator (-) subtracts numbers.

let x = 5; 
let y = 2; 
let z = x - y; 

Multiplying

The multiplication operator (*) multiplies numbers.

let x = 5;
let y = 2;
let z = x * y;

Dividing

The division operator (/) divides numbers.

let x = 5;
let y = 2;
let z = x / y;

Remainder

The modulus operator (%) returns the division remainder.

let x = 5;
let y = 2;
let z = x % y;

In arithmetic, the division of two integers produces a quotient and a remainder. In mathematics, the result of a modulo operation is the remainder of an arithmetic division.

Incrementing

The increment operator (++) increments numbers.

let x = 5; 
x++; 
let z = x; 

Decrementing

The decrement operator (--) decrements numbers.

let x = 5;
x--;
let z = x;

Exponentiation

The exponentiation operator (**) raises the first operand to the power of the second operand.

let x = 5;
let z = x ** 2;

x ** y produces the same result as Math.pow(x,y):

let x = 5;
let z = Math.pow(x,2);

Operator Precedence

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

let 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 subtraction (-). And (as in school mathematics) the precedence can be changed by using parentheses. When using parentheses, the operations inside the parentheses are computed first:

let x = (100 + 50) * 3;

When many operations have the same precedence (like addition and subtraction or multiplication and division), they are computed from left to right:

let x = 100 + 50 - 3;
let x = 100 / 50 * 3;