JSFiddle - React, Tailwind, and code Playground

JavaScript

var a= ['a','b','c','a'];
var b= ['a','d','f','c'];

    var unique = $.grep(a, function(element) {
        return $.inArray(element, b) == -1;
    });
     
    var unique2 = $.grep(b, function(element) {
        return $.inArray(element, a) == -1;
    });
var result = unique + unique2;

alert(result);