HTML Forms

Form Validation

HTML can check user input before the form is sent, with no JavaScript at all. The browser shows a message and stops the submission if something is wrong.

Attribute	Rule
`required`	Must not be empty.
`type="email"` / `"url"`	Must look like an email / web address.
`minlength` / `maxlength`	Length of text.
`min` / `max` / `step`	Range of numbers and dates.
`pattern`	Must match a regular expression.

<form>
  <input type="text" name="username" required minlength="3" maxlength="15">
  <input type="email" name="email" required>
  <input type="tel" name="phone" pattern="03[0-9]{9}" title="Format: 03001234567">
  <input type="number" name="age" min="13" max="99">
  <button>Sign up</button>
</form>