Pre-Increment

let counter = 2;

const preIncrement = ++counter;
// counter = counter + 1
// perIncrement = counter;
// -> 값을 먼저 증가시킨 다음에 해당 변수에 할당
console.log(`preIncrement: ${preIncrement}, counter: ${counter}`); // 3, 3

Post-Increment

let counter = 2;

const postIncrement = counter++;
// postIncrement = counter;
// counter = counter + 1;
// -> 해당 변수에 할당한 다음에 값을 증가
console.log(`postIncrement: ${postIncrement}, counter: ${counter}`); // 2, 3