How to ignore repeated values in array + javascript code example

Example 1: javascript remove duplicates from array

unique = [...new Set(arr)];   // where arr contains duplicate elements

Example 2: remove duplicates from array javascript

function onlyUnique(value, index, self) {
  return self.indexOf(value) === index;
}

// usage example:
var a = ['a', 1, 'a', 2, '1'];
var unique = a.filter(onlyUnique);

console.log(unique); // ['a', 1, 2, '1']