CODEWITHSUNDEEP
javascripthttphttp-referer
tim
tim

Reputation: 2039

Where does document.referrer come from?

I have the following script at http://localhost/test.html:

<script>
alert(document.referrer);
</script>

If I access it directly the result is an empty alert, which isn't surprising.

If I link from a different document at http://example.com/different.html, the alert will be that URL, again, not surprising.

What is suprising to me is that, if I intercept the HTTP request and change the Referer Header:

GET /test.html HTTP/1.1
Host: localhost
Referer: test

Then the alert will still alert the original URL, not test.

So where does document.referrer come from if not from the referer HTTP Header? Is it not influenced by the HTTP request at all? Is there a standard for this, or do different browsers handle it differently? And is there a way to influence it, without creating a new file linking to the code myself?

Upvotes: 3

Views: 6824

Answers (3)

freedev
freedev

Reputation: 30217

Referrer header your have intercepted is the request done by the client to the server. The client already know which is the referring page, you cannot fool it.

Upvotes: 1

Xepe
Xepe

Reputation: 235

The value is set by the browser, I mean the browser is setting the value "test" when you are doing the http request.

Upvotes: 0

radyz
radyz

Reputation: 1714

Per MDN documentation:

document.referrer:

Returns the URI of the page that linked to this page.

Further notes on why it displays empty to you:

The value is an empty string if the user navigated to the page directly (not through a link, but, for example, via a bookmark). Since this property returns only a string, it does not give you DOM access to the referring page.

More info can be found at: MDN

Now looking at the developer tools from both Chrome, Firefox and IE I can see the header is being set to: Referer:https://www.google.com/ whenever I hit a search result from google and this value is being set automatically by the browser. How it's set depends on browser implementor but this is the corresponding document describing the header value RFC 7231

The "Referer" [sic] header field allows the user agent to specify a
URI reference for the resource from which the target URI was obtained (i.e., the "referrer", though the field name is misspelled).

Upvotes: 0

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