只刷新一次浏览器

<script>
function fresh()
{
if(location.href.indexOf("?reload=true")<0)
{
location.href+="?reload=true";
}
}
setTimeout("fresh()",300);
document.onkeydown = function()
{
if(event.keyCode==116) {
event.keyCode=0;
event.returnValue = false;
}
}
document.oncontextmenu = function() {event.returnValue = false;}
</script>