Set a search field to be a required part of form submission:
document.getElementById("mySearch").required = true;
Click the button to set the required property for the search field.
<!DOCTYPE html> <html> <body> <form action="/action_page.php"> Search: <input type="search" id="mySearch" name="filter"> <input type="submit"> </form>/* w ww. j av a 2 s . c om*/ <button onclick="myFunction()">Test</button> <p id="demo"></p> <script> function myFunction() { document.getElementById("mySearch").required = true; document.getElementById("demo").innerHTML = "The required property was set."; } </script> </body> </html>