                        課程
                    
                        /前端開發
                        
                            /JavaScript
                        
                        /JS動畫效果

onmouseover事件觸發的疑惑？

http://www.xianlaiwan.cn/video/2879/0

這節課4分14秒的代碼，明明”分享“已經在父盒子div1之外了，將div1綁定onmouseover事件后，為什么鼠標移動到”分享“上仍然可以觸發？？而類似的下面的這段代碼卻無法觸發alert指令？？

<!DOCTYPE html>
<html>
?<head>
??<meta charset="utf-8">
??<title></title>
??<style type="text/css">
??*{
???margin: 0;
???padding: 0;
??}
???.container #share{
????width: 20px;
????height: 50px;
????background: blue;
????position: absolute;
????left:200px;
????top:75px;
???}
???.container{
????width: 200px;
????height: 200px;
????background: red;
????position: relative;
????left: -200px;
????top: 0px;
???}
??</style>
??<script type="text/javascript">
???window.onload=function (){
????var container = document.getElementsByClassName('container')
????container.onmouseover= function (){
?????startMove();?????
????}
???}
???function startMove(){
????alert(123);
???}
??</script>
?</head>
?<body>
??<div class="container">
???<span id="share">
????分享
???</span>
??</div>
?</body>
</html>