87,955
社区成员
![](https://csdnimg.cn/release/cmsfe/public/img/topic.427195d5.png)
![](https://csdnimg.cn/release/cmsfe/public/img/me.40a70ab0.png)
![](https://csdnimg.cn/release/cmsfe/public/img/task.87b52881.png)
![](https://csdnimg.cn/release/cmsfe/public/img/share-circle.3e0b7822.png)
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>this is lab</title>
<script src="http://apps.bdimg.com/libs/jquery/1.9.1/jquery.min.js"></script>
<script type="text/javascript">
function a(){
var b=document.getElementById("b").val();
console.log("b element is exist");
}
</script>
</head>
<body>
<script type="text/javascript">jQuery(function($){var b=$('#b').val();console.log("b element is exist");});</script>
<p>js执行时元素未加载</p>
<input type="text" value="a" id="b" />
</body></html>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>this is lab</title>
<script type="text/javascript">
function a(){
var b=document.getElementById("b").val();
console.log("b element is exist");
}
</script>
</head>
<body>
<script type="text/javascript">a();</script>
<p>js执行时元素未加载</p>
<input type="text" value="a" id="b" />
</body></html>