Html code validate email address

HTML does not have a built-in way to validate email addresses. However, you can use JavaScript or a regular expression to validate an email address. Here are a few examples:

Using JavaScript:

<form>
  <input type="email" id="email" name="email">
  <button type="submit">Submit</button>
</form>

<script>
  const emailInput = document.getElementById('email');
  emailInput.addEventListener('input', function() {
    const email = emailInput.value;
    const emailRegex = /^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$/;
    if (!emailRegex.test(email)) {
      alert('Invalid email address');
    }
  });
</script>

Using a regular expression:

<form>
  <input type="email" id="email" name="email">
  <button type="submit">Submit</button>
</form>

<script>
  const emailInput = document.getElementById('email');
  emailInput.addEventListener('input', function() {
    const email = emailInput.value;
    const emailRegex = /^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$/;
    if (!emailRegex.test(email)) {
      alert('Invalid email address');
    }
  });
</script>

Using HTML5 pattern attribute:

<form>
  <input type="email" id="email" name="email" pattern="[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}">
  <button type="submit">Submit</button>
</form>

Note that the HTML5 pattern attribute is not supported in older browsers, and the regular expression used in the examples above is not foolproof. It's always a good idea to use a more robust email validation library or service if you need to validate email addresses in a production environment.

Here's a breakdown of the regular expression used in the examples above:

^ matches the start of the string
[a-zA-Z0-9._%+-]+ matches one or more of the following characters: letters (both uppercase and lowercase), numbers, dot (.), hyphen (-), underscore (_), percent (%), plus sign (+)
@ matches the @ symbol
[a-zA-Z0-9.-]+ matches one or more of the following characters: letters (both uppercase and lowercase), numbers, dot (.), hyphen (-)
\. matches a period (.) character
[a-zA-Z]{2,} matches the domain extension (it must be at least 2 characters long)
$ matches the end of the string

This regular expression matches most common email address formats, but it's not perfect and may not match all valid email addresses.

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Html code validate email address