/* Clear searchbox-input field */
function clear_text() {
    var search_input = document.getElementById("keyword");
    if (search_input.value == 'trefwoord') {
        search_input.value = "";
    }
}

/* Set default text in searchbox-input field */
function set_text() {
    var search_input = document.getElementById("keyword");
    if (search_input.value == '') {
        search_input.value = "trefwoord";
    }
}