lastScrollY && scrollY > 50){ headerUp = false; isReturning = false }else if(scrollY < lastScrollY){ headerUp = true; if(lastScrollY > 50 && scrollY < 250){ isReturning = true }else{ isReturning = false } }; if(scrollY < 50){ isReturning = true } lastScrollY = scrollY">
半身机器人