想要完成下面的效果圖，目前進(jìn)度，move：方法達(dá)不到想要的自動(dòng)以速度位移2的速度移動(dòng),

var enemy = new Enemy(30,50,50,2);
enemy.draw();
enemy.moove();
function Enemy(x,y,size,speed){
          this.x = x,
          this.y = y,
          this.size = size,
          this.speed = speed //反彈系數(shù)
        }

        /**
         * 原型方法
         * @type {draw描繪出10個(gè)怪獸，clear清除畫布，move移動(dòng)怪獸隊(duì)列}
         */
        Enemy.prototype = {
            draw:function(){
                 for(let i=0;i<10;i++){
                   enemys[i] = new Image();
                   enemys[i].src ='./img/enemy.png';
                   enemys[i].onload = function(){
                      enemy.x += 50;
                      context.drawImage(enemys[i], enemy.x, enemy.y, enemy.size, enemy.size);
                    };
                 }
              },
              clears:function(){
                context.clearRect(30, 0, canvas.width, canvas.height);
              },
              // move:function(){
              //     var length = enemys.length; 
              //     if(enemy.x+enemy.speed > canvas.width 
              //     || enemy.x + enemy.speed < 0 
              //     || enemy.y + enemy.speed > canvas.height
              //     || enemy.y + enemy.speed < 0
              //     ){speed  *=-1}
              //     enemy.x +=enemy.speed;
              //     enemy.clears();

              //     enemy.draw();
              //     // context.drawImage(planeImage, plane.x, plane.y, plane.width, plane.height);          
              //     requestAnimationFrame(enemy.move);
              // },
             move:function(){
              enemy.x +=enemy.speed;
              enemy.clears();
              enemys.splice(0,enemys.length);
              enemy.draw();
              // requestAnimationFrame(enemy.move());
             }
        }