var _t1 = 0; //打开页面时等待图片载入的时间，单位为秒，可以设置为0
var _t2 = 2; //图片轮转的间隔时间
var _tnum = 4; //焦点图个数
var _tn = 1;//当前焦点
var _tl =null;
_tt1 = setTimeout('change_img()',_t1*1000);
function change_img(){
setFocus(_tn);
_tt1 = setTimeout('change_img()',_t2*1000);
}
function setFocus(i){
if(i>_tnum){_tn=1;i=1;}
_tl?document.getElementById('focusPic'+_tl).style.display='none':'';
document.getElementById('focusPic'+i).style.display='block';
_tl=i;
_tn++;
}