let c = 0;
console.log(c + 1); // outputs 1
console.log(c); outputs 0, since in the last statement you didn't changed the original value, just used it.
console.log(c++); // will output c then increment c. So it prints the old value: 0
console log(c); will output 1 (result of previous increment)
console.log(++c); // will increment c and then output it new value: 2