JavaScript Arithmetic
A typical thing to do with numbers is arithmetic.
JavaScript Arithmetic Operators
Arithmetic operators perform arithmetic on numbers (literals or variables).
| Operator | Description |
|---|---|
| + | Addition |
| - | Subtraction |
| * | Multiplication |
| / | Division |
| % | Modulus |
| ++ | Increment |
| -- | Decrement |
Arithmetic Operations
A typical arithmetic operation operates on two numbers.
The two numbers can be literals:
or variables:
or expressions:
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:
The subtraction operator (-) subtracts numbers.
The multiplication operator (*) multiplies numbers.
The division operator (/) divides numbers.
The modular operator (%) returns the division remainder.
The increment operator (++) increments numbers.
The decrement operator (--) decrements numbers.
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
| Value | Operator | Description | Example |
|---|---|---|---|
| 19 | ( ) | Expression grouping | (3 + 4) |
| 18 | . | Member | person.name |
| 18 | [] | Member | person["name"] |
| 17 | () | Function call | myFunction() |
| 17 | new | Create | new Date() |
| 16 | ++ | Postfix Increment | i++ |
| 16 | -- | Postfix Decrement | i-- |
| 15 | ++ | Prefix Increment | ++i |
| 15 | -- | Prefix Decrement | --i |
| 15 | ! | Logical not | !(x==y) |
| 15 | typeof | Type | typeof x |
| 14 | * | Multiplication | 10 * 5 |
| 14 | / | Division | 10 / 5 |
| 14 | % | Modulo division | 10 % 5 |
| 14 | ** | Exponentiation | 10 ** 2 |
| 13 | + | Addition | 10 + 5 |
| 13 | - | Subtraction | 10 - 5 |
| 12 | << | Shift left | x << 2 |
| 12 | >> | Shift right | x >> 2 |
| 11 | < | Less than | x < y |
| 11 | <= | Less than or equal | x <= y |
| 11 | > | Greater than | x > y |
| 11 | >= | Greater than or equal | x >= y |
| 10 | == | Equal | x == y |
| 10 | === | Strict equal | x === y |
| 10 | != | Unequal | x != y |
| 10 | !== | Strict unequal | x !== y |
| 6 | && | And | x && y |
| 5 | || | Or | x || y |
| 3 | = | Assignment | x = y |
| 3 | += | Assignment | x += y |
| 3 | -= | Assignment | x -= y |
| 3 | *= | Assignment | x *= y |
| 3 | /= | Assignment | x /= y |
Red entries indicates experimental or proposed technology (ECMASScript 2016 or ES7)
 |
Expressions in parentheses are fully computed before the value is used in the rest of the expression. |
|---|
Test Yourself with Exercises!
Exercise 1 » Exercise 2 » Exercise 3 » Exercise 4 » Exercise 5 »
