An instance of type 'UnityEngine.BoxCollider2D' is...

Hi, I am getting this error code on my new js script - Assets/Scripts/MovementScript.js(80,88): BCE0020: An instance of type 'UnityEngine.BoxCollider2D' is required to access non static member 'size'.

First of all, i am not sure what this means Secondly it says the error is on this line - if(vm <= 0 && contact.point.y <= transform.position.y - (BoxCollider2D.size.y/2) && Vector2.Angle(Vector2.up, contact.normal) <= slopeLimit){

I have checked through everything but i am still not sure what the problem is.

Here is my entire code incase you need it -

 #pragma strict
 var moveSpeed : float = 8;
 var jumpSpeed : float = 25;
 var fallSpeed : float = 64;
 var maxFallSpeed : float = 60;
 var maxUpSpeed : float = 25;
 var slopeLimit : float = 45;
 var dashSpeed : float = 120;
 var fly : boolean;
  
 private var vm : float;
 var onGround : boolean;
 private var xScale : float;
 private var h : float;
 private var v : float;
 private var jump : boolean;
 private var anim : Animator;
 private var boxcoll : BoxCollider2D; //If boxCollider2D is used replace w/ ... private var boxColl : BoxCollider2D;
  
 function Start () {
         xScale = transform.localScale.x; //Get correct starting Orientation for player.
         anim = gameObject.GetComponent("Animator"); //Get Animations for character
         boxcoll = GetComponent(BoxCollider2D); //if boxCollider2D is used replace w/... boxColl = GetComponent(BoxCollider2D);
 }
  
 function Update () {
         h = Input.GetAxisRaw("Horizontal"); //get horizontal input
         v = Input.GetAxisRaw("Vertical"); //get vertical input
         jump = Input.GetKey(KeyCode.Space); //get jump input
 }
  
 function FixedUpdate(){
         if(onGround && jump){ //Are we grounded can we jump?
                 vm = jumpSpeed;
         }
        
         var moveH : float = h * moveSpeed * Time.deltaTime; //Smooth horizontal movement
         //Flip character orientation
         if(h < 0){
                 transform.localScale.x = -xScale;
         } else if(h > 0){
                 transform.localScale.x = xScale;
         }
        
         anim.SetFloat("VM", vm); //Animate VM parameter
         anim.SetBool("Grounded", onGround); //Animate Grounded parameter
         rigidbody2D.AddForce(Vector2.right * moveH); //Apply horizontal movement
         rigidbody2D.AddForce(Vector2.up * vm); //Apply vertical movement
        
         if(fly){ //Can we fly?
                 if(v > 0){
                         //Fly like a bird!!!
                         vm += v * Time.deltaTime * 20;
                 } else {
                         //Uh oh it's gravity
                         vm -= fallSpeed * Time.deltaTime;
                 }
         } else {
                 //Gravity ... ouch!
                 vm -= fallSpeed * Time.deltaTime;
         }
        
         vm = Mathf.Clamp(vm, -maxFallSpeed, maxUpSpeed); //Clamp vertical speeds
         rigidbody2D.velocity = Vector2.zero; //Stop movement if there is no input
         onGround = false; //Clear out grounding check
 }
  
 function OnCollisionEnter2D(c : Collision2D){
         CheckCollision(c);
 }
  
 function OnCollisionStay2D(c : Collision2D){
         CheckCollision(c);
 }
  
 function CheckCollision(c : Collision2D){
         for(var contact in c.contacts){
                 //Check for floor hit
                 //If boxCollider2D is used replace circCollider.radius w/ (boxCollider2D.size.y/2)
                 if(vm <= 0 && contact.point.y <= transform.position.y - (BoxCollider2D.size.y/2) && Vector2.Angle(Vector2.up, contact.normal) <= slopeLimit){
                         onGround = true;
                         vm = Mathf.Max(0, vm);
                 }
         }
  }
  

Please ask if you need any more information.