Remove unsorted array duplicates using vanilla JavaScript

RemoveDuplicates

// Sample array
var collection = [1, 3, 7, 9, 0, 2, 5, 3, 8, 10, 2, 11, 7, 1, 7, 4, 6, 8, 1, 0];

/* O(n²) complexity on worst case scenarios, but O(n) on best scenarios */

/* 2. Resize the array with two nested loops, but it goes one forward comparing and another backwards removing
      The result is a faster interaction because we are removing duplicated ahead before Forward hits it */
function BackForwardUnique(arr){
  for(var forward = 0; forward < arr.length; forward++){
    for (var backward = arr.length - 1; backward > forward; backward--){
      if (arr[forward] === arr[backward]){
        arr.splice(backward, 1);
      }
    }
  }
  return arr;
}



/* 1. Make a O(n²) */
/*    This prevents multiple resizes and instances per interaction. i.e.: splice */

function MoveOnlyUnique(arr){
    var newArr = [], hasRepeated = false;
    
    if(arr.length > 0){
        newArr.push(arr[0]);
    }
    
    for (var i = 1; i < arr.length; i++){      
        hasRepeated = false;
        for (var j = 0; j < newArr.length; j++){
            if (arr[i] === newArr[j]){
                hasRepeated = true;
                break;
            }
        }
        if (!hasRepeated){
            newArr.push(arr[i]);
        }
    }
    return newArr;
}