Arithmetic Operators

Used for performing mathematical operations:

+ — addition
- — subtraction
* — multiplication
/ — division
% — remainder
** — exponentiation (ES6)
++ — increment (adds 1)
-- — decrement (subtracts 1)

The unary plus is an operator used to convert a value to a number.

The unary plus tries to convert the value after it into a number type.
This is useful when you explicitly want to cast a string or other type to a number.

It’s called “unary” because it works with one operand (unlike binary plus a + b, which uses two).

let str = "42";
let num = +str;
console.log(num); // 42 (number)
console.log(typeof num); // "number"

Increment and Decrement

Increment (++) and decrement (--) are unary operators in JavaScript used to increase or decrease a variable’s value by 1.

Increment ++

Prefix form (++x):

Increases the variable by 1.
Returns the new value (after increment).

let x = 5;
let y = ++x; // x becomes 6, y gets the new value
console.log(x); // 6
console.log(y); // 6

Postfix form (x++):

Increases the variable by 1.
Returns the old value (before increment).

let x = 5;
let y = x++; // y gets 5, then x becomes 6
console.log(x); // 6
console.log(y); // 5

Decrement --

The decrement operator decreases the value of a variable by 1.

Prefix form (--x):

Decreases the variable by 1.
Returns the new value (after decrement).

let x = 5;
let y = --x; // x becomes 4, y gets the new value
console.log(x); // 4
console.log(y); // 4

Postfix form (x--):

Decreases the variable by 1.
Returns the old value (before decrement).

let x = 5;
let y = x--; // y gets 5, then x becomes 4
console.log(x); // 4
console.log(y); // 5