Concat multiple arrays into one array without duplicates [duplicate]

Answer 1

var a = ["1", "2", "3"];
var b = ["3", "4", "5"];
var c = ["4", "5", "6"];

var d = [];

var hash = [];
AddToHash(a);

AddToHash(b);

AddToHash(c);

function AddToHash(arr) {
  for (var i = 0; i < arr.length; i++) {
    if (!hash[arr[i]]) {
      hash[arr[i]] = 1;
    } else
      hash[arr[i]] += 1;
  }
}

for (var i = 0; i < hash.length; i++) {
    d.push(i);
}
console.log(d);

Hope this helps