// Usage: <span class="blink">
var blinkTimerId;

// Set blinking interval. 
function SetBlinking(enable)
{
    if (enable)
        blinkTimerId = setInterval("Blink()", 650);
    else
        clearInterval(blinkTimerId);
}

// Blink content of span if className is 'blink'.
function Blink()
{
    var element;
    var elements = document.getElementsByTagName("SPAN");

    for (var index = 0; index < elements.length; index++)
    {
        element = elements[index];
        if (element.className == "blink")
            element.style.visibility = element.style.visibility == "" ? "hidden": "";
    }
}

// Enable / disable blinking.
SetBlinking(true);
onunload = function()
    {
        SetBlinking(false);
    };