In JavaScript, the ++ & -- operators increment and decrement the value of a variable respectively and we can apply them either after or before a variable.

• ++x (pre-increment): Increment x by 1, then use the new value of x in the expression in which x resides.
• x++ (post-increment): Use the current value of x in the expression in which x resides, then increment x by 1.
• --x (pre-decrement): Decrement x by 1, then use the new value of x in the expression in which x resides.
• x-- (post-decrement): Use the current value of x in the expression in which x resides, then decrement x by 1.

Example:

let counter = 1

let riddle = counter++
console.log(riddle)
// 1

let mystery = ++counter
console.log(mystery)
// 3