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<!DOCTYPE html> <html> <body> <form action="https://www.w3schools.com/action_page.php" method="get"> Name: <input type="text" id="myInput" name="fname" required> <input type="submit" value="Submit"> </form> <p><strong>Note:</strong> The oninvalid event is not supported in Internet Explorer 9 and earlier.</p> <script> document.getElementById("myInput").oninvalid = function() {myFunction()}; function myFunction() { alert("You must fill out the form!"); } </script> </body> <!-- Mirrored from www.w3schools.com/jsref/tryit.asp?filename=tryjsref_oninvalid_dom by HTTrack Website Copier/3.x [XR&CO'2014], Wed, 21 Dec 2022 17:39:59 GMT --> </html>
