removing dublicates from array please explain me elaborate

Question

what is the process going throught behind
var array = [1,2,2,3,4,5]
var uniqueArray= array.filter((item, index) => array.indexOf(item)=== index);

Answer 1

daneillonge

Starting with the filter(), it is an array method that creates a new array with every element in an array that passes a test. filter() method passes each item/element and index to
the anonymous function to be tested and in this case, the test is (array.indexOf(item)=== index).

The indexOf() is another array method and it searches the array for an element and returns its position/index if found. If the element is present more than once, the indexOf method returns the position of the [first occurrence(the first match)]

The test:
Index of the first occurrence of item 1: array[0] equals the index of current item 1: array[0] - true, this item is returned to the new array
Index of the first occurrence of item 2: array[1] equals the index of current item 2: array[1] - true this item is returned to the new array
Index of the first occurrence of item 2: array[1] equals the index of current item 2: array[2] - false -this item is not
Testing continues until every element in the array has been tested.

Clear as mud, I bet.
https://code.sololearn.com/Wv9uv5uMs9S4/#html