WHEN CREATING NEW INSTANCE

      var enemy = new Enemy();
      enemy.init(this.mapParser.getPathPositions(), this.mapParser.getStartPosition(), 2, 10);
      this.enemies.push(enemy);
      this.enemiesToCome--;

AND MY ACTUAL "Enemy" object - move method:

  this.update = function () {
    if(this.direction==0) {
      this.position[1]-=this.speed;
    } else if(this.direction==1) {
      this.position[0]+=this.speed;
    } else if(this.direction==2) {
      this.position[1]+=this.speed;
    } else if(this.direction==3) {
      this.position[0]-=this.speed;
    }
  }


When the "update" method is called it affects all instances.