1、实现原理：利用onmouseover与onmouseout事件
2、整体代码：
<!DOCTYPE html>
<html>
<head lang="en">
<meta charset="UTF-8">
<title></title>
</head>
<body>
<img src="images/jd1.png" alt="" id="pic"/>
<script>
var pic = document.getElementById("pic");
pic.onmouseover = function(){
pic.onmouseout = function(){
pic.src = "图片1";
}
pic.src = "图片2";
}
</script>
</body>
</html>