javascript - Loops- forEach, for, for....of, for...in

Question

I am not able to understand the difference between all these loops, can anyone share a link or some article which will help me understand these loops in more details in terms of efficiency, speed, usability etc.

In the below code, how can I best understand these differences?

const digits = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];

for (let i = 0; i < digits.length; i++) {
  console.log(digits[i]);
}

const digits = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];

for (const index in digits) {
  console.log(digits[index]);
}

const digits = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
for (const index of digits) {
  console.log(digits[index]);
}

Answer 1

for loop : This is the common method of iterating an array where we use i as index to access the elements in the array letters. MDN Docs for reference

var letters = ["a","b","c"];
for (let i = 0; i < letters.length; i++)
{
    console.log("Index : "+i, "Value : "+letters[i]);
}