Where did you install Firefox from? Help Mozilla uncover 3rd party websites that offer problematic Firefox installation by taking part in our campaign. There will be swag, and you'll be featured in our blog if you manage to report at least 10 valid reports!

Rechercher dans l’assistance

Évitez les escroqueries à l’assistance. Nous ne vous demanderons jamais d’appeler ou d’envoyer un SMS à un numéro de téléphone ou de partager des informations personnelles. Veuillez signaler toute activité suspecte en utilisant l’option « Signaler un abus ».

Learn More

JavaScript in firefox.cfg can't access `document`

  • 3 réponses
  • 0 a ce problème
  • 1 vue
  • Dernière réponse par jazali

more options

As I understand, `autoconfig.js` (with `firefox.cfg`) can be used to have JavaScript run during startup to control Firefox's UI elements.

I have set up `autoconfig.js` in my `/usr/lib/firefox-developer-edition/defaults/pref` folder (I'm on EndeavourOS Linux). As instructed here, I've already put the two required files, `autoconfig.js` and `firefox.cfg` in their correct folders (`/usr/lib/firefox-developer-edition/defaults/pref` and `/usr/lib/firefox-developer-edition` in my machine).

The file `firefox.cfg` contains the following code:

 //
 (() => {
   var tabbar = document.getElementById("TabsToolbar");
 })();


However, every time I run Firefox, this message will appear:

 "Failed to read the configuration file. Please contact your system administrator."


If I empty out the `firefox.cfg` file, Firefox will run normally without showing the error message. It will also run normally if I just have something like this in the file:

 //
 (() => {
   var testVar = "";
 })();


I don't understand why the JavaScript code can't access the Firefox UI elements through `document` or `window.document`. If `autoconfig.js` isn't build for that, what should I use to change my browser's UI elements through JavaScript?

Thank you.

As I understand, `autoconfig.js` (with `firefox.cfg`) can be used to have JavaScript run during startup to control Firefox's UI elements. I have set up `autoconfig.js` in my `/usr/lib/firefox-developer-edition/defaults/pref` folder (I'm on EndeavourOS Linux). As instructed [https://support.mozilla.org/en-US/kb/customizing-firefox-using-autoconfig here], I've already put the two required files, `autoconfig.js` and `firefox.cfg` in their correct folders (`/usr/lib/firefox-developer-edition/defaults/pref` and `/usr/lib/firefox-developer-edition` in my machine). The file `firefox.cfg` contains the following code: // (() => { var tabbar = document.getElementById("TabsToolbar"); })(); However, every time I run Firefox, this message will appear: "Failed to read the configuration file. Please contact your system administrator." If I empty out the `firefox.cfg` file, Firefox will run normally without showing the error message. It will also run normally if I just have something like this in the file: // (() => { var testVar = ""; })(); I don't understand why the JavaScript code can't access the Firefox UI elements through `document` or `window.document`. If `autoconfig.js` isn't build for that, what should I use to change my browser's UI elements through JavaScript? Thank you.
Captures d’écran jointes

Modifié le par jazali

Solution choisie

Note that you need a lot more code to be able to access a browser window (i.e. add an observer that is triggered when you open a window).


// start autoconfig.cfg with a comment line
try {
 function ConfigJS() { Services.obs.addObserver(this, 'chrome-document-global-created', false); }
 ConfigJS.prototype = {
  observe: function (aSubject) { aSubject.addEventListener('DOMContentLoaded', this, {once: true}); },
  handleEvent: function (aEvent) {
   let document = aEvent.originalTarget;
   let window = document.defaultView;
   let location = window.location;

   if (/^(chrome:(?!\/\/(global\/content\/commonDialog|browser\/content\/webext-panels)\.x?html)|about:(?!blank))/i.test(location.href)) {
    if (window._gBrowser) { //place your code here
       var tabbar = window.document.getElementById("TabsToolbar");
    }  // gBrowser
   }   // location
  }    // handleEvent
 };    // prototype
 if (!Services.appinfo.inSafeMode) { new ConfigJS(); }
} catch(e) {Cu.reportError(e);}

Lire cette réponse dans son contexte 👍 0

Toutes les réponses (3)

more options

Did you disable the sandbox via autoconfig.js ?

Content of autoconfig.js:

//start autoconfig.js with a comment line
pref("general.config.filename", "autoconfig.cfg");
pref("general.config.obscure_value", 0);
pref("general.config.sandbox_enabled", false);

Cela vous a-t-il été utile ?

more options

Solution choisie

Note that you need a lot more code to be able to access a browser window (i.e. add an observer that is triggered when you open a window).


// start autoconfig.cfg with a comment line
try {
 function ConfigJS() { Services.obs.addObserver(this, 'chrome-document-global-created', false); }
 ConfigJS.prototype = {
  observe: function (aSubject) { aSubject.addEventListener('DOMContentLoaded', this, {once: true}); },
  handleEvent: function (aEvent) {
   let document = aEvent.originalTarget;
   let window = document.defaultView;
   let location = window.location;

   if (/^(chrome:(?!\/\/(global\/content\/commonDialog|browser\/content\/webext-panels)\.x?html)|about:(?!blank))/i.test(location.href)) {
    if (window._gBrowser) { //place your code here
       var tabbar = window.document.getElementById("TabsToolbar");
    }  // gBrowser
   }   // location
  }    // handleEvent
 };    // prototype
 if (!Services.appinfo.inSafeMode) { new ConfigJS(); }
} catch(e) {Cu.reportError(e);}

Cela vous a-t-il été utile ?

more options

Hi. Thank you very much for the answer! My script can now access `document` thanks to your code. But I'm still confused on how to implement the following into the snipped you provided:

 var tabbar = window.document.getElementById("TabsToolbar");
 function showHideTabbar() {
   var sidebarBox = window.document.getElementById("sidebar-box");
   var sidebarTST = sidebarBox.getAttribute("sidebarcommand");
   if (!sidebarBox.hidden && sidebarTST === "treestyletab_piro_sakura_ne_jp-sidebar-action") {
     tabbar.style.visibility = "collapse";
   }
   else {
     tabbar.style.visibility = "visible";
   }
 }
 var observer = new MutationObserver(showHideTabbar);
 observer.observe(window.document.getElementById("sidebar-box"), { attributes: true, attributeFilter: ["sidebarcommand", "hidden"] });


Its purpose is to hide the tab strip on top when Tree Style Tab is open on the sidebar.

I found that it worked when I ran it through the Browser Toolbox. But it had no effect when I put it into the `if (window._gBrowser) {}` scope. I'm not too familiar with JavaScript, so I can't quite figure out what's wrong.

Modifié le par jazali

Cela vous a-t-il été utile ?

Poser une question

Vous devez vous identifier avec votre compte pour répondre aux messages. Veuillez poser une nouvelle question, si vous n’avez pas encore de compte.