Javascript - Loop through sparse array and replace sparse values

Question

I\'m trying to loop through a sparse array and fill in sparse elements with a value.

[\'foo\', \'bar\', , , ,].map(el => el || \'default\') // returns

Answer 1

Just use a for loop:

for (i = 0; i < arr.length; i++) {
  if (arr[i] === undefined) 
    arr[i] = 'default'
}