<html>
<head>
<title>test</title>
<script language="javascript" type="text/javascript">
var btn = document.getElementById("mybtn");
btn.onclick = function(){
alert(this.id);
};
</script>
</head>
<body>
<div align="center">
<input type="button" id="mybtn" value = "click" />
</div>
</body>
</html>
为什么 btn是空的呢
<head>
<title>test</title>
<script language="javascript" type="text/javascript">
var btn = document.getElementById("mybtn");
btn.onclick = function(){
alert(this.id);
};
</script>
</head>
<body>
<div align="center">
<input type="button" id="mybtn" value = "click" />
</div>
</body>
</html>
为什么 btn是空的呢
window.onload = function() {
var btn = document.getElementById("mybtn");
btn.onclick = function(){
alert(this.id);
};
}
window.onload = function() {
var btn = document.getElementById("mybtn");
btn.onclick = function(){
alert(this.id);
}
}