How does `Array.from({length: 5}, (v, i) => i)` work?

Question

I may be missing something obvious here but could someone breakdown step by step why Array.from({length: 5}, (v, i) => i) returns [0, 1, 2, 3, 4]

Answer 1

var arr1 = Array.from({
    length: 5 // Create 5 indexes with undefined values
  },
  function(v, k) { // Run a map function on said indexes using v(alue)[undefined] and k(ey)[0 to 4]
    return k; // Return k(ey) as value for this index
  }
);
console.log(arr1);