Custom validation form in CF7

Hi,

i would like to validate a text tag in contact form 7, to validate an italian car plate, this is my RegExp in JavaScript:

<script>

function targaCheck(){
var targaRExp = /^(([a-zA-Z]{2}\d{3}[a-zA-Z]{2})|(([a-zA-Z]{2}|roma)(\d{5}|\d{6})))$/i;
var targa = document.getElementById(“targa”).value;

if( targaRExp.test(targa) ) {
alert(“Correct”);
}else {
alert(“Incorrect”);
}
}
</script>
To validate the contact form 7 i have to use “add_filter” in function.php of my WP site, but when i insert my code it doesn’t work. (this is an example of code)
https://contactform7.com/2015/03/28/custom-validation/

add_filter( ‘wpcf7_validate_email*’, ‘custom_email_confirmation_validation_filter’, 20, 2 );

function custom_email_confirmation_validation_filter( $result, $tag ) {
$tag = new WPCF7_FormTag( $tag );

if ( ‘your-email-confirm’ == $tag->name ) {
$your_email = isset( $_POST[‘your-email’] ) ? trim( $_POST[‘your-email’] ) : ”;
$your_email_confirm = isset( $_POST[‘your-email-confirm’] ) ? trim( $_POST[‘your-email-confirm’] ) : ”;

if ( $your_email != $your_email_confirm ) {
$result->invalidate( $tag, “Are you sure this is the correct address?” );
}
}

return $result;
}
how can i do?

Please help me!

Thanks!