<!DOCTYPE html>
<html>
<body>
<form action="form_action.asp">
Search: <input type="search" id="mySearch" name="filter" required>
<input type="submit">
</form>
<p>Click the "Try it" button to find out if the search field must be filled out before submitting the form.</p>
<button onclick="myFunction()">Try it</button>
<p id="demo"></p>
<script>
function myFunction() {
var x = document.getElementById("mySearch").required;
document.getElementById("demo").innerHTML = x;
}
</script>
</body>
</html>