<script>
jQuery(document).ready( () => {

function getUrlParameter(name, url) {
    if (!url) {
        url = window.location.href;
    }
    name = name.replace(/[\[]/, '\\[').replace(/[\]]/, '\\]');
    var regex = new RegExp('[\\?&]' + name + '=([^&#]*)');
    var results = regex.exec(url);
    return results === null ? '' : decodeURIComponent(results[1].replace(/\+/g, ' '));
}
var coach = getUrlParameter('coachvar');


jQuery("[name='coach_field'").val(coach);
});

</script>