我有这个代码，适用于FF或Chrome，但IE没有。问题出在哪儿？ 谢谢
<!DOCTYPE html>
<html>
<head>
<script>
function displayResult()
{
document.getElementById("submit1").type = "hidden";
}
</script>
</head>
<body>
<form>
Email: <input type="text" id="email">
<input type="submit" id="submit1">
</form>
<button type="button" onclick="displayResult()">Display input type</button>
</body>
</html>