Set a field as required with jQuery

Hy,
First of all, compliments for the great plugin.
I tried to set the field “start” as required when the value of the field “jahrgang” is smaler than 2005.

As the field “jahrgang” has many values to be selected, so I tried the solution with jQuery.

jQuery(function($){
$(‘#jahrgang’).on(‘change’, function() {
if(this.value <= 2005){
$(‘#start’).attr(“aria-required”, “true”);
$(‘#start’).addClass(“wpcf7-validates-as-required”);
}else{
$(‘#start’).removeAttr(‘aria-required’);
$(‘#start’).removeClass(“wpcf7-validates-as-required”);
}
})
});

Unfortunately this code doesn’t work…

Would be very grateful if there would be a solution with jQuery.

Thanks and best reguards!
Peter

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