电商收付通JSAPI支付成功后页面不跳转到指定页面，为什么呀

function onBridgeReady(){

   WeixinJSBridge.invoke(

'getBrandWCPayRequest', {

"appId":"<?php echo $appid;?>",

"timeStamp":"<?php echo $time;?>",   

"nonceStr":"<?php echo $nonce;?>",

"package":"prepay_id=<?php echo $prepay_id;?>",

"signType":"RSA",   

"paySign":"<?php echo $sign;?>"

            },

function(res){

if(res.err_msg == "get_brand_wcpay_request:ok" )

window.location.href="支付成功后的跳转链接";

else if(res.err_msg =="get_brand_wcpay_request:cancel")

window.location.href="取消支付后的跳转链接";

else

{

alert('支付失败');

window.location.href="支付失败后的跳转链接";

                }

}); 

}

    if (typeof WeixinJSBridge == "undefined")

{

if( document.addEventListener )

{

           document.addEventListener('WeixinJSBridgeReady', onBridgeReady, false);

}

else if (document.attachEvent)

{

           document.attachEvent('WeixinJSBridgeReady', onBridgeReady); 

           document.attachEvent('onWeixinJSBridgeReady', onBridgeReady);

}

}

else

{

       onBridgeReady();

}