刚学ASP。NET时写的防止重复提交的脚本

内容是：
function _doPostBack(){};
if(typeof("__doPostBack")=="function")
{
    _doPostBack=__doPostBack;
    __doPostBack=_doPostBackNew;
}
document.attachEvent("onmousemove",_onmousemove);
var _isPosting=false;
var _divMask=null;
function _onmousemove()
{
    if(_divMask)
    with(_divMask.runtimeStyle)
    {
        left=event.clientX+document.body.scrollLeft-4;
        top=event.clientY+document.body.scrollTop-4;
    }
}
function _makeMask()
{
    var div=document.createElement("DIV");
    with(div.runtimeStyle)
    {
        position="absolute";
        zIndex=999999;
        fontSize="1px";
        left=event.clientX+document.body.scrollLeft-4;
        top=event.clientY+document.body.scrollTop-4;
        width="8px";
        height="8px";
        cursor="wait";
       
        backgroundColor="gray";
        filter="alpha(opacity=10)";
    }
    try
    {
        document.body.insertAdjacentElement("BeforeEnd",div);
        div.onblur=new Function("this.focus()");
        div.focus();
    }
    catch(x){}
   
    if(_divMask)_divMask.removeNode(true);
    _divMask=d