function doBuy() {
    var popupBuyBg = document.getElementById('popupBuyBg');
    var popupBuyContainer = document.getElementById('popupBuyContainer');

    popupBuyBg.style.display = '';
    popupBuyContainer.style.display = '';

}

function endBuy() {
    var popupBuyBg = document.getElementById('popupBuyBg');
    var popupBuyContainer = document.getElementById('popupBuyContainer');

    popupBuyBg.style.display = 'none';
    popupBuyContainer.style.display = 'none';
}

function checkBuy() {
    var result = false;
    var chkBox = document.getElementById('fldAgreed');

    result = ((chkBox != undefined) && (chkBox.checked == true));

    if (!result) {
        alert('U moet de algemene downloadvoorwaarden van de Management Executive Base accepteren alvorens u een artikel kunt downloaden!');
    }
    
    return result;
}