マウスの移動方向を検出するJavaScriptメソッド_JavaScriptスキル

function Start() {
  stage.addEventListener(MouseEvent.MOUSE_MOVE, CheckDirection);
}
Start();
var prevX=0;
var prevY=0;
var curX=0;
var curY=0;
 
var dirX:String="";
var dirY:String="";
function CheckDirection(e:MouseEvent) {
  trace("X movement: " + GetHorizontalDirection() + ", Y movement: " + GetVerticalDirection());
  e.updateAfterEvent();
}
function GetHorizontalDirection():String {
  prevX=curX;
  curX=stage.mouseX;
  if (prevX>curX) {
    dirX="left";
  } else if (prevX < curX) {
    dirX="right";
  } else {
    dirX="none";
  }
  return dirX;
}
function GetVerticalDirection():String {
  prevY=curY;
  curY=stage.mouseY;
  if (prevY>curY) {
    dirY="up";
  } else if (prevY < curY) {
    dirY="down";
  } else {
    dirY="none";
  }
  return dirY;
}