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<!DOCTYPE html> <html> <body> <form action="form_action.asp"> Search: <input type="search" id="mySearch" name="filter"> <input type="submit"> </form> <p>Click the "Try it" button to set the required property for the search field.</p> <p><strong>Tip:</strong> Click the "Submit" button before and after you have clicked the "Try it" button, to see the effect.</p> <button onclick="myFunction()">Try it</button> <p id="demo"></p> <script> function myFunction() { document.getElementById("mySearch").required = true; document.getElementById("demo").innerHTML = "The required property was set. The search field must now be filled out before submitting the form."; } </script> </body> </html>