檢查必要欄位是否輸入

function CheckFunc() {

var msg = "";
var oa = document.form;
if ( oa.no.value == "" ) msg = msg + "【號碼】尚未輸入\n";
if ( oa.names.value == "" ) msg = msg + "【姓名】尚未輸入\n";
if ( oa.bday.value == "" ) msg = msg + "【生日】尚未輸入\n";
if ( msg == "" ) {
return true;
}
else {
msg = msg + "\n※ 請務必輸入以上必要欄位後方可新增 ※";
alert ( msg );
return false;
}
}

========================================================

<form name="form" method="post" enctype="multipart/form-data" action="test.php">

號碼<input type="text" name="no"  value="" />
姓名<input type="text" name="names" value="" />
生日<input type="text" name="bday"  value="" />

<input type="submit" name="Send" id="Send" value="【送　出】" onclick="return CheckFunc();" />
</form>