& lt; Asp: Content ID="Content2 ContentPlaceHolderID"="ContentPlaceHolder1" runat="server" & gt; 
Var time=7200; 
Var minutes; 
Var seconds; 
Var con; 
The function showtime () {

Con=document. GetElementById (' & lt; % %=lab_sj. The ClientID & gt; '); 
Minutes=parseInt (time/60); 
60 seconds=time %; 
time--; 
Con. InnerHTML (minutes + ":" + seconds); 
If (time==0) {
Window. The alert (" end test!" ); 
Window. The location. Href='https://bbs.csdn.net/student/default.aspx'; 
} 
The else {
SetTimeout (" showtime () ", 1000); 
} 
} 
</script> 

 

 

Master page page, point button to start the countdown, with the document. The write tested first seconds can get id for the lab_sj object, immediately find next second object or object to null


Want to know the cause of the problem, and can have a solution, realize the master page page countdown function