效果：
代碼：
<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>效驗meail</title>
</head>
<body>
<br>
<center>
<form>
郵箱地址：<input name="meail_input_name" type = "text" id="meail_input_id" value="" placeholder="請輸入正確的郵箱">
<input name="meail_check_name" type = "button"id="meail_check_id" value="效驗郵箱" onclick="checkmeail()">
</form>
</center>
</br>
</body>
<script type="text/javascript">
function checkmeail(){
var meailaddress=document.getelementbyid("meail_input_id").value;
//長度
var meaillength = meailaddress.length;
//判斷含有@，“.”
var index1 = meailaddress.indexof("@");
var index2 = meailaddress.indexof(".");
var msg = "效驗輸入的郵箱號n";
msg = "@所在的索引：==：" index1;
msg = "\\\’.\\\’所在的索引：==：" index2;
msg ="郵箱地址：" meailaddress "n";
msg ="驗證郵箱地址的實例："
if (index1==-1||index2==-1||index1<index2) {
msg ="郵箱的基本要求:" "n";
msg ="必須含有\(zhòng)\\’@\\\’和\\\’.\\\’ n";
msg ="\\\’.\\\’必須在\\\’@\\\’后面n";
}else{
msg = "符合要求";
};
alert(msg);
}
</script>
</html>