function toUniqueArray(a){
var newArr = [];
for (var i = 0; i < a.length; i++) {
if (newArr.indexOf(a[i]) === -1) {
newArr.push(a[i]);
}
}
return newArr;
}
var colors = ["red","red","green","green","green"];
var colorsUnique=toUniqueArray(colors); // ["red","green"]
arr = [2, 2, 2, 1, 3, 3, 3,3, 4, 5];
arr = arr.sort().filter((item,i)=>!(arr[i] == arr[i+1] || arr[i-1]==arr[i]));
// this will remove all item which are repeating more then one
console.log(arr);
// [1, 4, 5]