防止在HTML5文本框上进行验证
为了避免验证，请使用HTML5中的formnovalidate属性。在该示例中，禁用了第二个按钮的验证：
<!DOCTYPE html>
<html>
<head>
<title>HTML formnovalidate attribute</title>
</head>
<body>
<form action = "new.php" method = "get">
Rank <input type = "number" name = "rank"><br>
<input type = "submit" value = "Submit"><br>
<input type = "submit" formnovalidate = "formnovalidate" value = "Submit with no validation">
</form>
</body>
</html>