++i vs. i++

++i vs. i++ in JavaScript

Same as in other languages:

• ++i (pre-increment) means "increment the variable; the value of the expression is the final value"

• i++ (post-increment) means "remember the original value, then increment the variable; the value of the expression is the original value"

Increment vs Post-increment in an array

I was confused as to what arr[index++] does in the removeDuplicates question

let index = 1;
for (let i = 0; i < arr.length - 1; i++) {
  if (arr[i] !== arr[i + 1]) {
    arr[index++] = arr[i + 1];
  }
}

Answer:

arr[index++] is the same as:

arr[index];
index = index + 1;

So in the loop above the would reference arr[1] and then assign the right hand value. AND THEN increment.

Resource:

• Variable Difference | Difference in i in loops
• https://stackoverflow.com/questions/34797524/js-while-loop-arrayi-how-does-it-work