微信支付完成后跳转到指定页面

html中根据前台支付后反馈信息成功与否跳转到相关页面
<script src="http://res.wx.qq.com/open/js/jweixin-1.0.0.js"></script>
<script type="text/javascript">
function show_qrcode()
{
var qrcode_url = '__qr_code__';
document.getElementById("qrcode_div").style.display = "block";
document.getElementById("wx_tip").style.display = "none";
document.getElementById("qrcode").src=qrcode_url;
}
//调用微信JS api 支付
function jsApiCall()
{
WeixinJSBridge.invoke(
'getBrandWCPayRequest',
__jsApiParameters__,
function(res){
if(res.err_msg=='get_brand_wcpay_request:fail'){
show_qrcode();
//alert('支付失败');
//location.href="__pay_url__";
}
if(res.err_msg=='get_brand_wcpay_request:cancel'){
show_qrcode();
//alert('支付取消');
//location.href="__pay_url__";
}
if(res.err_msg=='get_brand_wcpay_request:ok'){
alert('恭喜您支付成功');
location.href="__pay_url__";
}
}
);
}

function callpay()
{
if (typeof WeixinJSBridge == "undefined"){
if( document.addEventListener ){
document.addEventListener('WeixinJSBridgeReady', jsApiCall, false);
}else if (document.attachEvent){
document.attachEvent('WeixinJSBridgeReady', jsApiCall);
document.attachEvent('onWeixinJSBridgeReady', jsApiCall);
}
}else{
jsApiCall();
}
}

callpay();

</script>'