var width=document.documentElement.clientWidth||document.body.clientWidth;
var height=document.documentElement.clientHeight||document.body.clientHeight;
document.getElementById("ttttt").addEventListener("click",alert_box);
function alert_box()
{
    document.getElementById("con").style="display:none;"
    document.getElementById("alert_box").style="display:inline;position: absolute;left: 10px;top:0px;";
}
document.getElementById("alert_box").addEventListener(‘click‘,dis);
function dis(){
    document.getElementById("alert_box").style="display:none;"
    document.getElementById("con").style="display:block;"
}

js弹出窗口小特效-PHP