Description

hkyuwon

opened on Nov 18, 2017

Issue body actions

When I try to use [context] on xHR, I meet this error.
Script error: DOMException { }

// no problem
GM.xmlHttpRequest({method:"GET",url:"/",onload:function(r){console.log(r);}});

// error
GM.xmlHttpRequest({method:"GET",url:"/",context:{f:function(r){console.log(r);}}});
// error
GM.xmlHttpRequest({method:"GET",url:"/",context:{d:document}});

Reacted by Cerberus-tm

Activity

1. ccloli commented on Nov 20, 2017

   

   ccloli

   on Nov 20, 2017

   Contributor

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   I have this problem too, maybe it's related to #2647 . Try adding location.origin before the URL.
2. arantius

   changed the title [-]DOMException on GM.xmlHttpRequest[/-] [+]DOMException on GM.xmlHttpRequest when using `context`[/+] on Nov 21, 2017
3. arantius

   added this to the This milestone has been deleted milestone on Nov 21, 2017
4. arantius

   removed this from the This milestone has been deleted milestone on Jan 19, 2018
5. Mzyxptlk commented on Jan 3, 2021

   

   Mzyxptlk

   on Jan 3, 2021

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   I am also experiencing this issue. Minimal testcase:

   // ==UserScript==
   // @name     onload context bug
   // @grant    GM.xmlHttpRequest
   // @include  https://github.com/greasemonkey/greasemonkey/issues/2701
   // ==/UserScript==
   var does_not_work = function() {
     console.log('context called!');
   };
   GM.xmlHttpRequest({
     'url': location.origin,
     'onload': function(req) {
       console.log('onload called');
       if (req.context.call_me) {
         req.context.call_me();
       }
       else {
         console.log('nothing to call');
       }
     },
     'context': {
       'call_me': does_not_work
     }
   });
   console.log('sent request!');

   Loading this page with the above user script installed results in the following error:

   Script error in [Greasemonkey script null/onload context bug; version 1]:
   DataCloneError: The object could not be cloned.

   The error does not occur when the context object is empty (but obviously does_not_work is not called in that case either). Unfortunately I've not been able to find a useful backtrace.

   Reacted by Cerberus-tm
6. arantius commented on May 28, 2026

   

   arantius

   on May 28, 2026

   Collaborator

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   Using GitHub as the repro is not ideal as opening it spews hundreds of log entries to the console, but the above minimal test case on a simpler page does still log:

   Script error in [Greasemonkey script null/onload context bug]:
   DataCloneError: Function object could not be cloned.
   
7. arantius

   added

   confirmed

   on May 28, 2026
8. arantius

   changed the title [-]DOMException on GM.xmlHttpRequest when using `context`[/-] [+]DOMException on GM.xmlHttpRequest when `context` contains functions[/+] on May 28, 2026
9. arantius commented on May 28, 2026

   

   arantius

   on May 28, 2026

   Collaborator

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   https://wiki.greasespot.net/index.php?title=GM.xmlHttpRequest&diff=8643&oldid=7747

   I've noted the root issue in the documentation.
10. arantius commented on May 28, 2026

    

    arantius

    on May 28, 2026

    Collaborator

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    An even more minimal test script:

    // ==UserScript==
    // @name     GM issue 2701
    // @grant    GM.xmlHttpRequest
    // ==/UserScript==
    GM.xmlHttpRequest({
      'url': location.origin,
      'context': {
        'call_me': () => {},
      }
    });
11. arantius

    added this to the 4.14 milestone on May 28, 2026
12. arantius

    added a commit that references this issue on May 28, 2026

    Fix sanitizing port messages for GM.xhr.

    ac4a214
13. arantius commented on May 28, 2026

    

    arantius

    on May 28, 2026

    Collaborator

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    I've pushed a commit (see above) that should fix this, but I still need to test how it interacts with the upload handlers.
14. arantius commented on May 28, 2026

    

    arantius

    on May 28, 2026

    Collaborator

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    Actually, I rolled back the documentation I mentioned above -- the code change makes that untrue.
15. arantius commented on May 29, 2026

    

    arantius

    on May 29, 2026

    Collaborator

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    Test script https://github.com/greasemonkey/greasemonkey/blob/master/test/scripts/api-xhr-upload.user.js

    Logs upload progress and load, before the overall load. LGTM.
16. arantius

    closed this as completedon May 29, 2026

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