Testing of Pre-value CF7 form

<script text="text/javascript">
var getUrlParameter = function getUrlParameter(sParam) {
    var sPageURL = decodeURIComponent(window.location.search.substring(1)),
        sURLVariables = sPageURL.split('&'),
        sParameterName,
        i;
    for (i = 0; i < sURLVariables.length; i++) {
        sParameterName = sURLVariables[i].split('=');
        if (sParameterName[0] === sParam) {
            return sParameterName[1] === undefined ? true : sParameterName[1];
        }
    }
};

var firstname = getUrlParameter('fname');

     document.getElementById('yourfirstname').value = firstname;


</script>