include_once("./module/payment/lib/WxPayPubHelper/WxPayPubHelper.php");
//使用jsapi接口
$jsApi = new JsApi_pub();
//=========步骤1：通过code获得openid============
$openid = $_SESSION[‘openid‘];
//=========步骤2：使用统一支付接口，获取prepay_id============
$unifiedOrder = new UnifiedOrder_pub();

$unifiedOrder->setParameter("openid", $openid);//商品描述
$unifiedOrder->setParameter("body", "test");//商品描述
//自定义订单号，此处仅作举例

$timeStamp = time();
$out_trade_no = WxPayConf_pub::APPID . "$timeStamp";
$unifiedOrder->setParameter("out_trade_no", $out_trade_no);//商户订单号
$unifiedOrder->setParameter("total_fee", 100);//总金额
$unifiedOrder->setParameter("notify_url", WxPayConf_pub::NOTIFY_URL);//通知地址
$unifiedOrder->setParameter("trade_type", "JSAPI");//交易类型
//非必填参数，商户可根据实际情况选填
//$unifiedOrder->setParameter("sub_mch_id","XXXX");//子商户号
//$unifiedOrder->setParameter("device_info","XXXX");//设备号
$unifiedOrder->setParameter("attach", $re_wx[‘id‘] . "|" . $order_id);//附加数据

$prepay_id = $unifiedOrder->getPrepayId();
//=========步骤3：使用jsapi调起支付============
$jsApi->setPrepayId($prepay_id);
$jsApiParameters = $jsApi->getParameters();

header(‘Content-Type:application/json; charset=utf-8‘);
exit(json_encode($jsApiParameters));

$.ajax({
    type: "post",
    url: url,
    dataType: "json",
    data: {price:price,order_id:id},
    success: function(msg){
        var data = $.parseJSON(msg);
        $(‘#wx‘).attr(‘data-appid‘,data.appId);
        $(‘#wx‘).attr(‘data-time‘,data.timeStamp);
        $(‘#wx‘).attr(‘data-nonce‘,data.nonceStr);
        $(‘#wx‘).attr(‘data-pack‘,data.package);
        $(‘#wx‘).attr(‘data-sign‘,data.paySign);
        callpay();
    }
});

<script type="text/javascript">


    //调用微信JS api 支付
    function jsApiCall()
    {

        WeixinJSBridge.invoke(‘getBrandWCPayRequest‘,{

            "appId":$(‘#wx‘).attr(‘data-appid‘),
            "timeStamp":$(‘#wx‘).attr(‘data-time‘),
            "nonceStr":$(‘#wx‘).attr(‘data-nonce‘),
            "package":$(‘#wx‘).attr(‘data-pack‘),
            "signType":"MD5",
            "paySign":$(‘#wx‘).attr(‘data-sign‘)
        },function(res){
            // WeixinJSBridge.log(res.err_msg);
            if(res.err_msg == "get_brand_wcpay_request:ok")// 支付成功
            {

                var order_id=$(‘#order_id‘).val();
                location.href = "<{$config.web_url}>/pay/?m=fenhong&s=evaluate&order_id="+order_id;

            }
        });
    }
    function callpay()
    {
        //$("#form1").submit();
        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();
        }
    }
</script>

<div id="wx" data-appid="" data-time="" data-nonce="" data-pack="" data-sign="" style="display:none"></div>

异步调起微信支付