普通实现
<!DOCTYPE html><html lang="en"><head><meta charset="UTF-8"><title>键盘控制div移动</title><style type="text/css">.box{width:400px;height:600px;border:1px blue solid;position:absolute;margin-left:300px;}#item{width:80px;height:80px;background-color:red;position:absolute;left:0px;
