仿淘宝js放大镜效果核心代码malmg.onmouseover=function(){showimg.style.display="block";bigimg.style.display="inline";show_half=showimg.offsetHeight/2;maxWidth=smalmg.clientWidth-showimg.offsetWidth;maxHeight=smalmg.clientHeight-showimg.offsetHeight;//上面两个变量指明showimg允许活动的区域};smalmg.onmousemove=