How to set a regular expression for an input element value that checked against using HTML ?

Last Updated : 25 Dec, 2020

In this article, we will use <input> pattern attribute to set the regular expression pattern for an input field that checked against. The HTML <input> pattern attribute is used to specify the regular expression on which the input elements value is checked against. This attribute works with the following input types: text, password, date, search, email, etc. Use the Global title attribute to describe the pattern for helping the user.

Syntax:

<input pattern = "regular_exp">

Attribute Value: The pattern attribute is used to set the pattern of regular expression that enters into the input field.

Example: This example illustrates the use of pattern attribute in <input> element.

HTML

<!DOCTYPE html>
<html>

<head>
    <title>
        How to specify a regular expression
        that an input element's value
        is checked against?
    </title>
</head>

<body style="text-align: center;">
    <h1 style="color: green;">
        GeeksforGeeks
    </h1>

    <h3>
        How to specify a regular expression
        that an input <br>element's value
        is checked against?
    </h3>

    <form action="#">
        Name: <input type="text" name="Password"
            pattern="[A-Za-z]{10}" 
            title="Three letter Password">

        <input type="submit">
    </form>
</body>

</html>