Opcja warunków w HTML
<form action="" onsubmit="myFunction()">
<label for="fname">First name:</label><br>
<input type="text" id="fname" name="fname" value=""><br>
<label for="lname">Last name:</label><br>
<input type="text" id="lname" name="lname" value=""><br><br>
<input type="submit" value="Submit">
</form>
<script type="text/javascript">
function myFunction(){
var fname = document.getElementById("fname").value;
if(fname == '<>')
alert("Condition met")
}
</script>
Combative Coyote