function getWindowXCenter()
    {
    var x = window.innerWidth;
    return (x - (x / 2));
    }
    
function getWindowYCenter()
    {
    var y = window.innerHeight;
    return (y - (y / 2));
    }
    
function initLoader() 
    {
    var element = document.getElementById('_wait_Loader');
    var wrapper = document.getElementById('_wait_Loader_wrapper');
    wrapper.style.width = window.innerWidth + 'px';
    wrapper.style.height = window.innerHeight + 'px';
    var yElement = (element.offsetHeight / 2);
    var xElement = (element.offsetWidth / 2);
    element.style.top = (getWindowYCenter() - yElement) + 'px';
    element.style.left = (getWindowXCenter() - xElement) + 'px';
    }

function showLoader()
    {
    initLoader();
    var element = document.getElementById('_wait_Loader');
    var wrapper = document.getElementById('_wait_Loader_wrapper');
    wrapper.style.visibility = 'visible';
    }
    
function hideLoader()
    {
    var element = document.getElementById('_wait_Loader');
    var wrapper = document.getElementById('_wait_Loader_wrapper');
    wrapper.style.visibility = 'hidden';
    }