DOM element operation additions and deletions change

Get Web page width high var sheight=document.documentelement.scrollheight;var swidth=document.documentelement.scrollwidth;// Get the viewable area wide-height var wheight=document.documentelement.clientheight;var wwidth=document.documentelement.clientwidth;// Create Divvar omask=document.createelement ("div"); omask.id= "Mask"; omask.style.height=sheight+ "px"; omask.style.width= swidth+ "px";d ocument.body.appendChild (Omask);//Create Divvar ologin=document.createelement ("div"); ologin.id= "Login" ; ologin.innerhtml= "<div class= ' Logincon ' ><div id= ' close ' ></div></div>"; Document.body.appendChild (Ologin);//Gets the DOM element's wide-height var dheight=ologin.offsetheight;var dwidth=ologin.offsetwidth;o login.style.left= (wwidth-dwidth)/2+ "px"; ologin.style.top= (wheight-dheight)/2+ "px";

　　

Delete element Document.body.removeChild (omask);d ocument.body.removeChild (Ologin);

　　

DOM element operation additions and deletions change