html 简单的预缓存

切图生成html，加鼠标响应，预缓存

<style>
            .d4{
            width:190;
            height:170;
            background-image: url(images/未标题-1_09-16.jpg);
            cursor: pointer;
            }
            .d4:hover{
            width:190;
            height:170;
            background-image: url(images/1_09-16.jpg);
            cursor: pointer;
            }
            </style>
            <img src="data:images/1_09-16.jpg" style="display:none">
            <div  class="d4"></div>