run javascript when opening another page

Question

I'd like to open another web page from javascript (like default navigating, not fullscreen iframe or window.open) and run some javascript code upon loading it.

Steps:

Define a javascript function
Navigate to another page
Browser runs function in new page context

is there any way to achieve this? the only way I remember would be emulating this by loading the page using ajax, and replacing document.body.innerHtml, then running the function, but that would not change location.href, so e.g. the back button or bookmarks wouldn't work. also relative links had to be rewritten at loading, etc...

PS: I know that would be some ugly XSS, but it's needed for example when writing bookmarklets that load a page and fill in a form automatically.

If you own that page, then put the script there in the first place. — Joseph
– Joseph, Commented Apr 14, 2013 at 8:49

Paul · Accepted Answer · 2013-04-14 08:49:19Z

2

No, you can't do that. That would allow you to do things like steal cookies for session hijacking behind the scenes, so no browsers allow you to do it at all.

answered Apr 14, 2013 at 8:49

Paul

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fardjad · Accepted Answer · 2013-04-14 08:49:27Z

1

While there could be some legitimate use cases, for security reasons you can't do this unless the new page is on the same domain.

What you can do is to write a browser extension if the target browser has extensions support,

Or tell users to open the target page, and use your bookmarklet on that context.

answered Apr 14, 2013 at 8:49

fardjad

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3 Comments

nonchip Over a year ago

so the flow would be 'if(location.href!="..."){alert("Please run me again upon page load");location.href="..."}else{...}'?

nonchip Over a year ago

would replacing the whole page by an iframe even work, or would the browser ("the browser" being any generic navigator except IE :-P) forbid this because of XSS possibilities?

fardjad Over a year ago

Browsers don't allow altering iframes with external sources (for security reasons.)

bjelli · Accepted Answer · 2013-04-24 07:10:37Z

1

You can do all this stuff if you load the other page from your own server:

Say you want to load http://other.com in your site http://mine.org You write a tiny serverside script that you can call like this: http://mine.org/load.php?site1 (with the urls to all the sites you want to load listed inside load.php or in some database)

but now your site has the security problem: javascript embedded in http://other.com is run in your sites context.

edited Apr 24, 2013 at 7:10

answered Apr 14, 2013 at 9:09

bjelli

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nonchip · Accepted Answer · 2017-07-18 13:36:50Z

OK, reserch results:

Impossible methods:

using some persistent function to run on the new page (like I suggested in the question)
using an iframe replacing the whole page (ugly and forbidden by most browsers)

Overkill methods:

write a browser plugin
get the remote page owner to accept some GET argument and do the stuff for you

Remaining method 1, requiring user interaction:

(function(){
  if(self.location.href!=targetlocation){
    window.alert("Please run this bookmarklet again upon loading the page.");
    self.location.href=targetlocation;
  }else{
    doSomething();
  }
  return false;
})();

Remaining method 2, doing some nasty proxy stuff:

write some php/etc script to "proxy" the target page
now you can:
- use an iframe, because it's not cross-site anymore
- rewrite the page server-side before delivering to browser (doing "overkill method: GET argument" by yourself)

Example:

<?php //USAGE: ?uri=http://www.google.com&search[0]=L2dvb2dsZS8K&replace[0]=dGVzdAo=
  $page=file_get_contents($_GET["uri"]);
  $count = min(count($_GET["search"]),count($_GET["replace"]),100);
  for ($i = 0; $i < $count; $i++) {
    $page=preg_replace(base64_decode($_GET["search"][$i]),
                       base64_decode($_GET["replace"][$i]), $page);
  }
  echo $page;
?>

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