直接上代码：

window.onload = function () {
    initScreenSaver();
}

//0912 add
function ScreenSaver(settings){     
 
    this.settings = settings;     
        
    this.nTimeout = this.settings.timeout;     
                     
    document.body.screenSaver = this;     
    // link in to body events     
    document.body.onmousemove = ScreenSaver.prototype.onevent;     
    document.body.onmousedown = ScreenSaver.prototype.onevent;     
    document.body.onkeydown = ScreenSaver.prototype.onevent;     
    document.body.onkeypress = ScreenSaver.prototype.onevent;     
             
    var pThis = this;     
    var f = function(){pThis.timeout();}     
    this.timerID = window.setTimeout(f, this.nTimeout);     
}     
ScreenSaver.prototype.timeout = function(){     
   if ( !this.saver ){
      window.history.back(-1)//无动作跳转地址  
   }     
}     
ScreenSaver.prototype.signal = function(){     
   if ( this.saver ){     
      this.saver.stop();     
   }     
                 
   window.clearTimeout(this.timerID);     
                 
   var pThis = this;     
   var f = function(){pThis.timeout();}     
   this.timerID = window.setTimeout(f, this.nTimeout);     
}     
            
ScreenSaver.prototype.onevent = function(e){     
   this.screenSaver.signal();     
}     
            
            
var saver;     
function initScreenSaver(){
   saver = new ScreenSaver({timeout:20000});   //无动作时间  
}