function openProductView(){
    if (typeof WeixinJSBridge == "undefined")
        return false;

    var pid = "pDF3iY_G88cM_d-wuImym3tkVfG5";//只需要传递
    WeixinJSBridge.invoke(‘openProductViewWithPid‘,{
        "pid":pid
    },function(res){
        // 返回res.err_msg,取值 
        // open_product_view_with_id:ok 打开成功
        alert(res.err_msg);
        if (res.err_msg != "open_product_view_with_id:ok"){
            WeixinJSBridge.invoke(‘openProductView‘,{
                "productInfo":"{\"product_id\":\""+pid+"\",\"product_type\":0}"
            },function(res){ 
                alert(res.err_msg);
            });
        }
    });
}