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<html><body><h1>The input pattern attribute</h1><p>A form with a URL field that must start with http:// or https:// followed by at least one character:</p><form action="/action_page.php"> <label for="website">Homepage:</label> <input type="url" id="website" name="website" pattern="https?://.+" title="Include http://"> <input type="submit"></form></body></html>