How to use the pattern attribute to validate input fields against a specific regular expression?

Utpal Vishwas 673 11 May 2023

Utpal Vishwas

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I am Utpal Vishwas from Uttar Pradesh. Have completed my B. Tech. course from MNNIT campus Prayagraj in 2022. I have good knowledge of computer networking.

1 Answers

Aryan Kumar 11 May 2023

The pattern attribute is used to validate input fields against a specific regular expression. A regular expression is a sequence of characters that defines a search pattern. For example, the regular expression ^[a-zA-Z0-9]+<span class="math-inline">\ matches any string that consists of only letters and numbers. To use the pattern attribute, you simply need to set the attribute's value to the regular expression that you want to use. For example, the following code would use the regular expression `^[a-zA-Z0-9]+to validate the input fieldusername`:

Code snippet

<input type="text" name="username" pattern="^[a-zA-Z0-9]+$">

If the value of the input field does not match the regular expression, then the input field will be considered invalid.

Here are some examples of how to use the pattern attribute to validate input fields against specific regular expressions:

To validate an email address, you could use the regular expression ^[a-zA-Z0-9.!#<span class="math-inline">%&\'\*\+\\/\=?^\_\{|}~-]+@[a-zA-Z0-9-]+(?:\.[a-zA-Z0-9-]+)*`.
To validate a phone number, you could use the regular expression ^\d{10}<span class="math-inline">\. * To validate a date, you could use the regular expression `^\d{4}-\d{2}-\d{2}`.

The pattern attribute is a powerful tool that can be used to validate input fields against a variety of different regular expressions.

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How to use the pattern attribute to validate input fields against a specific regular expression?

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