How to detect if an array has empty items and remove them?

Question

Empty items are not falsey values; they are empty slots in an array.

> const someEmptyItems = ["index0",,,"index3"];
undefined

> someEmptyItems;
[ 'index0', <2 empty items>, 'index3' ]

> someEmptyItems[1];
undefined

> someEmptyItems.length;
4

Logging the array helps spot the empty array items nanually.

1. How can I detect empty array items programmatically?

2. How can I programmatically remove empty items from an array without mutating other (not-empty) values?

Answer 1

You could filter the array and return true for every visited element.

const
    sparseArray = ["index0",,,"index3"],
    notSparseArray = sparseArray.filter(_ => true);

console.log(notSparseArray);