Postfix увеличение
let x = 3;
y = x++;
Owlthegentleman
let x = 3;
y = x++;++x = x is now 2
x++ = x is now 3 but the showed value remains 2
x = is 3
x = 2 + (2 * 3)
x = 8
let a = 2;
b = ++a;