js实现简单锁屏功能实例

//********* 锁屏DIV ***************************function LockScreen(tag,title,width,height,url){  if (tag) //锁屏  {    var lockdiv = document.getElementById("lockscreen");    if (lockdiv!=null)    {      lockdiv.style.display = "block";      var subdiv = document.getElementById("subdialog");      if (subdiv!=null)      {        subdiv.style.display = "block";        document.getElementById("dialog1").src = url;      }          }else{      //创建新的锁屏DIV,并执行锁屏      var tabframe= document.createElement("div");      tabframe.id = "lockscreen";      tabframe.name = "lockscreen";      tabframe.style.top = '0px';      tabframe.style.left = '0px';      tabframe.style.height = '100%';      tabframe.style.width = '100%';      tabframe.style.position = "absolute";      tabframe.style.filter = "Alpha(opacity=10)";      tabframe.style.backgroundColor="#000000";      tabframe.style.zIndex = "99998";      document.body.appendChild(tabframe);      tabframe.style.display = "block";      //子DIV      var subdiv = document.createElement("div");      subdiv.id = "subdialog";      subdiv.name = "subdialog";      subdiv.style.top = Math.round((tabframe.clientHeight-height)/2);      subdiv.style.left = Math.round((tabframe.clientWidth-width)/2);      subdiv.style.height = height+'px';      subdiv.style.width = width+'px';      subdiv.style.position = "absolute";      subdiv.style.backgroundColor="#000000";       subdiv.style.zIndex = "99999";      subdiv.style.filter = "Alpha(opacity=100)";      subdiv.style.border = "1px";      //subdiv.onmousemove = mouseMoveDialog;      //subdiv.onmousedown = control_onmousedown;      //subdiv.onmouseup = mouseUp;      document.body.appendChild(subdiv);      subdiv.style.display = "block";      //subdiv.onclick=UNLockScreen;      var iframe_height = height-30;      var titlewidth = width;      var html = "<table border='0' cellpadding='0' cellspacing='0'>"      html += "<tr><td></td><td>";      html += "<table><tr><td><font color='#FFFFFF'><b>"+title+"</b></font></td><td style='width:30px' valign='top'><img src='/images/images/close.gif' ></img></td></tr></table>";      html += "</td><td></td></tr>";      html += "<tr><td></td><td style='height:100px;'><iframe id='dialog1' frameborder=0 style='width:"+titlewidth+"px;height:" + iframe_height + "px' src='"+url+"'></iframe></td><td></td></tr>";      html += "<td></td><td></td><td></td>";      html += "</table>";      subdiv.innerHTML = html;    }  }else{    //解屏    var lockdiv = document.getElementById("lockscreen");    if (lockdiv!=null)    {      lockdiv.style.display = "none";    }    var subdiv = document.getElementById("subdialog");    if (subdiv!=null)    {      subdiv.style.display = "none";    }  }}function UNLockScreen(){  LockScreen(false);}

//阻止F5或者鼠标右键刷新,使锁屏失效。document.onkeydown = function(){ if(event.keyCode==116) { event.keyCode=0; event.returnValue = false; }}document.oncontextmenu = function() {event.returnValue = false;}