<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Untitled Document</title></head>
<body>
<script type="text/javascript">
function create(elementId){
var name=document.getElementById('main');
document.write(name);
var s=document.createTextNode('sadferwetwpo');
name.appendChild(s);
}
create("main");
</script>
<div id="main">你好啊</div>
</body>
</html>
为什么我得到的总是空值 document.write(name);这一句得到总是为空值?????
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Untitled Document</title></head>
<body>
<script type="text/javascript">
function create(elementId){
var name=document.getElementById('main');
document.write(name);
var s=document.createTextNode('sadferwetwpo');
name.appendChild(s);
}
create("main");
</script>
<div id="main">你好啊</div>
</body>
</html>
为什么我得到的总是空值 document.write(name);这一句得到总是为空值?????
1、声明create方法
2、调用create方法
……
3、加载<div id="main">
在你调用create时,div[id='main']还没加载,所以找不到解决方法:
把
create("main");
这句替换成如下语句:
window.onload = function(){ create("main"); };
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Untitled Document</title></head>
<body>
<div id="main">你好啊</div>
<script type="text/javascript">
function create(elementId){
var name=document.getElementById('main');
document.write(name);
var s=document.createTextNode('sadferwetwpo');
name.appendChild(s);
}
create("main");
</script>
</body>
</html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Untitled Document</title>
<script type="text/javascript">
function create(elementId){
var name=document.getElementById('main');
document.write(name);
var s=document.createTextNode('sadferwetwpo');
name.appendChild(s);
}
</script>
</head>
<body>
<div id="main">你好啊</div>
<script>create("main")</scirpt>
</body>
</html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Untitled Document</title></head>
<body>
<div id="main">你好啊</div>
<script type="text/javascript">
function create(elementId){
var name=document.getElementById('main');
document.write(name);
var s=document.createTextNode('sadferwetwpo');
name.appendChild(s);
}
create("main");
</script>
</body>
</html>
或者
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Untitled Document</title>
<script type="text/javascript">
function create(elementId){
var name=document.getElementById('main');
document.write(name);
var s=document.createTextNode('sadferwetwpo');
name.appendChild(s);
}
window.onload=create;
</script>
</head>
<body>
<div id="main">你好啊</div>
</body>
</html>