使用JavaScript在刷新时将查询字符串附加到url

Question

I am trying to read a label and append its value as a query string once the user hits the refresh button on their browser. The code I have so far is:

 function AppendQueryString() {
            var currUrl = document.location;
            var trackingNbr = $("#lblTrackingNbr").text();
           if (window.location.href.indexOf("?TrackingNumber=") <= 0 && trackingNbr !== null) {
                document.location = currUrl + "?TrackingNumber="+ trackingNbr;  
            }
        }

        window.onbeforeunload = AppendQueryString(); 

The problem is, the trackingNbr variable is always null even though the label has the value before I hit refresh. What am I doing wrong or is there a better way of doing this ?

Answer 1

SessionStorage would be a good solution, with something like this:

sessionStorage.setItem("trackingNbr", trackingNbr);

When the refresh button is clicked, you can pull this value back from session storage easily:

var trackingNbr = sessionStorage.getItem("trackingNbr");

Security: Because this is session storage rather than local storage, the value will be cleared from the browser when the session ends. Note that only your domain can access whatever you put into either session or local storage. However, a knowledgeable end user can read the value by using developer tools in any of the major browsers.