function moveUp(element) {
    element = document.getElementById(element);
    for(var i = 0; i < element.options.length; i++) {
        if(element.options[i].selected == true) {
            if(i != 0) {
                var temp = new Option(element.options[i - 1].text, element.options[i - 1].value);
                var temp2 = new Option(element.options[i].text, element.options[i].value);
                element.options[i - 1] = temp2;
                element.options[i - 1].selected = true;
                element.options[i] = temp;
            }
        }
    }
}

function moveDown(element) {
    element = document.getElementById(element);
    for(var i = (element.options.length - 1); i >= 0; i--) {
        if(element.options[i].selected == true) {
            if(i != (element.options.length - 1)) {
                var temp = new Option(element.options[i + 1].text, element.options[i + 1].value);
                var temp2 = new Option(element.options[i].text, element.options[i].value);
                element.options[i + 1] = temp2;
                element.options[i + 1].selected = true;
                element.options[i] = temp;
            }
        }
    }
}

function updateList(element, field) {
    element = document.getElementById(element);
    field = document.getElementById(field);
    field.value = '';
    for(var i = 0; i < element.options.length; i++) {
        if (i == 0) {
            field.value += element.options[i].value;
        } else {
            field.value += ',' + element.options[i].value;
        }
    }
}

function swap(element) {
    var j = 0;
    element = document.getElementById(element);
    for(var i = 0; i < element.options.length; i++) {
        if(element.options[i].selected == true) {
            j++;
            switch (j) {
                case 1:
                    var i1 = i;
                    var temp = new Option(element.options[i].text, element.options[i].value);
                    break;
                case 2:
                    var i2 = i;
                    var temp2 = new Option(element.options[i].text, element.options[i].value);
                    break;
            }
        }
    }
    if (j != 2) {
        alert('Selecteer 2 items om te verwisselen.');
    } else {
        element.options[i1] = temp2;
        element.options[i1].selected = true;
        element.options[i2] = temp;
        element.options[i2].selected = true;
    }
}