function Trim(str)
{
    return str.replace(/^\s+|\s+$/g, '');
}

function ToggleDisplayNone(id)
{
    var el = document.getElementById(id);
    el.style.display = (el.style.display != 'none' ? 'none' : '' );
}

function HideIfRequiredFieldsAreFilled(hideThis,txt1,txt2,txt3,txt4) 
{
    var str1 = document.getElementById(txt1).value;
    var str2 = document.getElementById(txt2).value;
    var str3 = document.getElementById(txt3).value;
    var str4 = document.getElementById(txt4).value;
    if (Trim(str1) != "" && 
        Trim(str2) != "" && 
        Trim(str3) != "" && 
        Trim(str4) != "")
    {
        ToggleDisplayNone(hideThis);
    }
}