如何添加一个正则表达式，以在HTML中检查 元素的值？
使用 pattern属性设置正则表达式，以检查<input>元素的值。您可以尝试运行以下代码来实现 模式 属性-
示例
<!DOCTYPE html>
<html>
<head>
<title>HTML novalidate attribute</title>
</head>
<body>
<form action = "" method = "get" novalidate>
Student Name<br><input type = "name" name = "sname"><br>
Rank<br><input type = "number" name = "rank"><br>
Student Country <br><input type = "text" name = "ccode" pattern="[A-Za-z]{3}" title = "country code"><br>
<input type = "submit" value = "Submit">
</form>
</body>
</html>