SOURCE

function unique(arr) {
  var result = []
  for (var i = 0,
  len = arr.length; i < len; i++) {
    var item = arr[i]
    if (result.indexOf(item) == -1) {
      result.push(item)
    }
  }
  return result
}
var arr1 = [1, 1, 2, 4, 56, 3, '3']
var arr2 = unique(arr1) console.log(arr2)