Removing Duplicates in Arrays

I am trying to pass a function that removes duplicates from an array. It should handle strings, object, integers as well. In my code so far I am showing that it will handle strings but nothing else. How can Imake this function universalto handle numbers,handle arrays,handle objects, and mixed types?

let unique = (a) => a.filter((el, i ,self) => self.indexOf(el) ===i);

In this function I hav unique() filtering to make a new array which checks the element and index in the array to check if duplicate. Any help would be appreciated.