Home How to get Url Hash (#) from server side
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How to get Url Hash (#) from server side

Ricky Supit
Ricky Supit Published in 2008-11-25 15:43:16Z

I know on client side (javascript) you can use windows.location.hash but could not find anyway to access from the server side.

Obsidian Reply to 2015-08-18 10:38:08Z

We had a situation where we needed to persist the URL hash across ASP.Net post backs. As the browser does not send the hash to the server by default, the only way to do it is to use some Javascript:

  1. When the form submits, grab the hash (window.location.hash) and store it in a server-side hidden input field Put this in a DIV with an id of "urlhash" so we can find it easily later.

  2. On the server you can use this value if you need to do something with it. You can even change it if you need to.

  3. On page load on the client, check the value of this this hidden field. You will want to find it by the DIV it is contained in as the auto-generated ID won't be known. Yes, you could do some trickery here with .ClientID but we found it simpler to just use the wrapper DIV as it allows all this Javascript to live in an external file and be used in a generic fashion.

  4. If the hidden input field has a valid value, set that as the URL hash (window.location.hash again) and/or perform other actions.

We used jQuery to simplify the selecting of the field, etc ... all in all it ends up being a few jQuery calls, one to save the value, and another to restore it.

Before submit:

$("form").submit(function() {
  $("input", "#urlhash").val(window.location.hash);

On page load:

var hashVal = $("input", "#urlhash").val();
if (IsHashValid(hashVal)) {
  window.location.hash = hashVal;

IsHashValid() can check for "undefined" or other things you don't want to handle.

Also, make sure you use $(document).ready() appropriately, of course.

Mauricio Scheffer
Mauricio Scheffer Reply to 2008-11-25 19:27:15Z

RFC 2396 section 4.1:

When a URI reference is used to perform a retrieval action on the identified resource, the optional fragment identifier, separated from the URI by a crosshatch ("#") character, consists of additional reference information to be interpreted by the user agent after the retrieval action has been successfully completed. As such, it is not part of a URI, but is often used in conjunction with a URI.

(emphasis added)

Julien Oster
Julien Oster Reply to 2008-11-25 15:45:55Z

That's because the browser doesn't transmit that part to the server, sorry.

patridge Reply to 2008-12-30 11:16:13Z

Probably the only choice is to read it on the client side and transfer it manually to the server (GET/POST/AJAX). Regards Artur

You may see also how to play with back button and browser history at Malcan

webaholik Reply to 2016-03-09 21:34:02Z

Possible solution for GET requests:

New Link format: http://example.com/yourDirectory?hash=video01

Call this function toward top of controller or http://example.com/yourDirectory/index.php:

function redirect()
    if (!empty($_GET['hash'])) {
        /** Sanitize & Validate $_GET['hash']
               If valid return string
               If invalid: return empty or false
        $validHash = sanitizeAndValidateHashFunction($_GET['hash']);
        if (!empty($validHash)) {
            $url = './#' . $validHash;
        } else {
            $url = '/your404page.php';
        header("Location: $url");
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