JS Arithmetic Operators

Arithmetic Operation JavaScript

JavaScript provides the user with five arithmetic operators: +, -, *, / and %. The operators are for addition, subtraction, multiplication, division and remainder respectively.

Addition

Syntax

a + b

Usage

2 + 3          // returns 5
true + 2       // interprets true as 1 and returns 3
false + 5      // interprets false as 0 and returns 5
true + "bar"   // concatenates the boolean value and returns "truebar"
5 + "foo"      // concatenates the string and the number and returns "5foo"
"foo" + "bar"  // concatenates the strings and returns "foobar"

Hint: There is a handy increment operator that is a great shortcut when you're adding numbers by 1.

Subtraction

Syntax

a - b

Usage

2 - 3      // returns -1
3 - 2      // returns 1
false - 5  // interprets false as 0 and returns -5
true + 3   // interprets true as 1 and returns 4
5 + "foo"  // returns NaN (Not a Number)

Hint: There is a handy decrement operator that is a great shortcut when you're subtracting numbers by 1.

Multiplication

Syntax

a * b

Usage

2 * 3                // returns 6
3 * -2               // returns -6
false * 5            // interprets false as 0 and returns 0
true * 3             // interprets true as 1 and returns 3
5 * "foo"            // returns NaN (Not a Number)
Infinity * 0         // returns NaN
Infinity * Infinity  // returns Infinity

Division

Syntax

a / b

Usage

3 / 2                // returns 1.5
3.0 / 2/0            // returns 1.5
3 / 0                // returns Infinity
3.0 / 0.0            // returns Infinity
-3 / 0               // returns -Infinity
false / 5            // interprets false as 0 and returns 0
true / 2             // interprets true a 1 and returns 0.5
5 + "foo"            // returns NaN (Not a Number)
Infinity / Infinity  // returns NaN

Remainder

Syntax

a % b

Usage

3 % 2          // returns 1
true % 5       // interprets true as 1 and returns 1
false % 4      // interprets false as 0 and returns 0
3 % "bar"      // returns NaN

!Important! As you can see, you cannot perform any sort of operations on Infinity.

Source: The amazing MDN.