Saving color to PlayerPrefs

Im trying to save color to PlayerPrefs, but heard that you can easily save color to PlayerPrefsX. Well, the problem I have is that when im trying to use PlayerPrefsX it says that it is unknown identifier. Im using Javascript so can this be a problem here or should I use something else to save the color.

EDIT:

Here is saving:

 #pragma strict

 var rotatingEnemy : GameObject;

 function Update () {
         if(Input.GetMouseButtonUp(0)){
     
             var hit : RaycastHit2D = Physics2D.Raycast(Camera.main.ScreenToWorldPoint(Input.mousePosition), Vector2.zero);
             var hitObject = hit.collider;
             
             switch(hitObject.name){
                 case "Background":
                     break;
                     
                 default:
                     PlayerPrefsX.SetColor("enemyColor", hitObject.renderer.material.color);
                     rotatingEnemy.renderer.material.color = hitObject.renderer.material.color;
                     break;
             }
         }
 }

Here is loading:

 function Start () {
     renderer.material.color = PlayerPrefsX.GetColor("enemyColor");
 }

Error code:

Assets/scripts/Game/EnemyChangeColor.js(4,35): BCE0005: Unknown identifier: 'PlayerPrefsX'.

and

Assets/scripts/ShopPreviewRotatingEnemyColor.js(16,41): BCE0005: Unknown identifier: 'PlayerPrefsX'.