filter 와 indexOf 를 이용한 중복제거 방법

var a = ['a', 1, 'a', 2, '1'];
var unique = a.filter((v, i, s) => s.indexOf(v) === i); // returns ['a', 1, 2, '1']


Ref

https://stackoverflow.com/questions/1960473/get-all-unique-values-in-a-javascript-array-remove-duplicates