Скачать или смотреть Arithmetic Operators - JavaScript Tutorial - w3Schools Chapter-10 English

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

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.

Subtracting
The subtraction operator (-) subtracts numbers.

Multiplying
The multiplication operator (*) multiplies numbers.

Dividing
The division operator (/) divides numbers.

Remainder
The modulus operator (%) returns the division remainder.

Incrementing
The increment operator (++) increments numbers.

Decrementing
The decrement operator (--) decrements numbers.

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

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

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.

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

JavaScript Operator Precedence Values