Is it possible to set localStorage or Session variable in asp.net page and read it in javascript on the other page?

Question

As in question. Is it possible to set variable in asp.net page in localStorage and retrieve it on the other page?

How to set localStorage variable in asp.net. Is it possible? After that I could read variable using:

localStorage.getItem('UserID');

Solution 1

I guess You can't. The whole point of local storage is that it is local and You can manipulate it only from javascript. If You need to pass values between server and client You need to use some transport technology - cookies, ajax calls, hidden fields etc. It will all depend on how your application is organized, what kind of information is being stored, its volume, whether you want to redirect or not, but in all cases this should be done using javascript since that's the only way to access data stored in localStorage.

Solution 2

Old post yes, but knowledge is always good.

You can set the local or session storage from asp.net (indirectly). Since we can set up javascript code in asp.net and insert into the client side, there's no difference with the session or local storage.

Try this from server side

string script = string.Format("sessionStorage.userId= '{0}';", "12345");
ClientScript.RegisterClientScriptBlock(this.GetType(), "key", script, true);

That will set the session (you could do local) storage variable to the value 12345.

Solution 3

I've done this by using cookies:

Default.aspx.cs code behind:

HttpCookie userIdCookie = new HttpCookie("UserID");
userIdCookie.Value = id.ToString();
Response.Cookies.Add(userIdCookie);
Response.Redirect("~/ImagePage.html");

HttpCookie Expires wasn't setted. It expires default with session.

html page javascript:

function OnLoad() {
var userId = getCookie('UserdID');
if (userId == null)
    window.location = "http://localhost:53566/Default.aspx";        
}

function getCookie(cookieName) {
    var cookieValue = document.cookie;
    var cookieStart = cookieValue.indexOf(" " + cookieName + "=");
    if (cookieStart == -1) {
        cookieStart = cookieValue.indexOf("=");
    }
    if (cookieStart == -1) {
        cookieValue = null;
    }
    else {
        cookieStart = cookieValue.indexOf("=", cookieStart) + 1;
        var cookieEnd = cookieValue.indexOf(";", cookieStart);
        if (cookieEnd == -1) {
            cookieEnd = cookieValue.length;
        }
        cookieValue = unescape(cookieValue.substring(cookieStart, cookieEnd));
    }
    return cookieValue;
}

Solution 4

I think setting session variable in page & read variable in javascript of another page is possible. But, if you are looking out for localstorage that won't be. It needs javascript. For session variable e.g.
A.aspx

<% Session["username"]="Donald Duck"; %>

B.aspx

>  <script type="text/javascript">
>       var user = "<%= Session["username"] %>";
>       document.write(user);
>  </script>

Solution 5

you can use asp:HiddenField

after changed localstorage or sessionStorage you fill hidden field and use in code behind.

View more solutions

Comments

[Krzysztof Cieslak]

string myScriptValue = "function callMe() {alert('You pressed Me!'); }"; ScriptManager.RegisterClientScriptBlock(this, this.GetType(), "myScriptName", myScriptValue, true); But i dont think mixing code behind and javascript is a good idea - just a sugestion. Anytime you need to make a simple change/update to your javascript you'll have to re-build your project, which means re-deploying instead of simply pushing out a single .js file.

[mashet]

The second page isn't .aspx page, but html + js only.

[Vishwajeet Kulkarni]

Yes, it would be possible in html+js too.

[mashet]

I've tried this way, but it needs Postback. In my case it isn't possible. Thanks for answers ;)

[Mike W]

you can output Javascript from ASP .Net so anything that can be done in Javascript can be done in ASP .Net