JS+HTML实现的圆形可点击区域示例【3种方法】

<img src="images/lanlvseImg.png" usemap="#Map" /> 
<map name="Map" id="Map">
 <area shape="circle" coords="100,100,50" href="http://.baidu." rel="external nofollow" target="_blank"/>
</map>

<div id="circle"></div>
#circle{
 background:red;
 width:100px;
 height:100px;
 border-radius:50%;
}

document.onclick = function(e) { 
 var r = 50; 
 var x1 = 100;
 var y1 = 100;
 var x2= e.clientX;
 var y2= e.clientY; 
 var distance = Math.abs(Math.sqrt(Math.pow(x2 - x1, 2) + Math.pow(y2 - y1, 2))); 
 if (distance <= 50)
 alert("Yes!"); 
}