Definition and Usage
The pattern attribute specifies the pattern used to validate the input field.
A pattern refers to a regular expression.
Note: The pattern attribute applies to the following types: text, search, url, telephone, email, and password.
Tip: Please use the standard "title" attribute to describe the schema.
grammar
<input pattern="regexp">
值 regexp
描述 规定用于输入字段的模式。
<!DOCTYPE HTML>
<html>
<body>
// 只能包含三个字母的文本字段（数字或特殊字符）：
<form action="/example/html5/demo_form.asp" method="get">
国家代码：<input type="text" name="country_code" pattern="[A-z]{3}"
title="三个字母的国家代码" />
<input type="submit" />
</form>
</body>
</html>