<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
<script type="text/javascript">
function isEmail() {
var emailValue = document.getElementsByName("email")[0].value;
if (emailValue.indexOf("@") == -1) {
alert("请输入@符号");
} else {
alert("恭喜你，我们的界面友好吧")
}
}
</script>
</head>
<body>
email:
<input type="text" name="email">
<input type="button" onclick="isEmail()" value="提交">
</body>
</html>