2.5 JS Arithmetic

Arithmetic Operations

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

Example 1: JavaScript Arithmetic part 2

var x = 100 + 50;

or variables:

Example 2: JavaScript Arithmetic part 3

var x = a + b;

or expressions:

Example 3: JavaScript Arithmetic part 4

var x = (100 + 50) * a;

Adding

The addition operator (+) adds numbers:

Example 4: JavaScript Arithmetic part 5

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

Subtracting

The subtraction operator (-) subtracts numbers.

Example 5: JavaScript Arithmetic part 6

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

Multiplying

The multiplication operator (*) multiplies numbers.

Example 6: JavaScript Arithmetic part 7

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

Dividing

The division operator (/) divides numbers.

Example 7: JavaScript Arithmetic part 8

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

Remainder

The modulus operator (%) returns the division remainder.

Example 8: JavaScript Arithmetic part 9

var x = 5;
var y = 2;
var 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.

Example 9: JavaScript Arithmetic part 10

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

Decrementing

The decrement operator (--) decrements numbers.

Example 10: JavaScript Arithmetic part 11

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

Exponentiation

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

Example 11: JavaScript Arithmetic part 12

var x = 5;
var z = x ** 2;          // result is 25

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

Example 12: JavaScript Arithmetic part 13

var x = 5;
var z = Math.pow(x,2);   // result is 25

Operator Precedence

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

Example 13: JavaScript Arithmetic part 14

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 subtraction (-).
• And (as in school mathematics) the precedence can be changed by using parentheses:

Example 14: JavaScript Arithmetic part 15

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 15: JavaScript Arithmetic part 16

var x = 100 + 50 - 3;