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| Arithmetic Operation |
JavaScript provides five arithmetic operators: +, -, *, / and %. The operators are for addition, subtraction, multiplication, division and remainder, respectively.
Addition
Syntax
a + b
Caution
The + serves as an arithmetic operator and for concatenating strings. Take extra caution when dealing with numbers versus string data types.
If a and b data types are both numbers, their value will add.
If a is a number and "b" is a string, their value will concatenate into a string.
If "a" and "b" are both strings, their value will concatenate into a string.
Usage
2 + 3 // returns 5
5 + "3" // returns "53"
"10" + "40" // returns "1040"
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"
Note: 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 -2
5 - "foo" // returns NaN (Not a Number)
Note: 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
Also referred to as the "modulus" or "modulo" operator.
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
Increment
Syntax
a++, ++a or a+=
Usage
// Postfix
x = 3; // declare a variable
y = x++; // y = 4, x = 3
// Prefix
var a = 2;
b = ++a; // a = 3, b = 3
// Advanced
var a = 4;
var b = 5;
a += b; //a = 9, b = 5
Decrement
Syntax
a--, --a or a-=
Usage
// Postfix
x = 3; // declare a variable
y = x--; // y = 3, x = 3
// Prefix
var a = 2;
b = --a; // a = 1, b = 1
// Advanced
var a = 9;
var b = 4;
a -= b; //a = 5, b = 4
!Important! You cannot perform any sort of operations on Infinity.
Exponentiation
Syntax
a ** b
Usage
3 ** 2; // returns 9
3 ** 0; // returns 1
3 ** -Infinity; // returns 0
!Important! As you can see, you cannot perform any sort of operations on Infinity.
Source: The amazing MDN