Help:Locating broken scripts

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If you have problems with local gadgets or user scripts, these problems are often created by broken JavaScript code (the programming language that gadgets are written in) or undeclared dependencies on other code.

To track down the problematic code and place that needs fixing, you will have to use the developer tools of your web browser. This tool, combined with a special URL, will help you to identify the broken scripts.

How-to

Be sure you have an up-to-date configuration

First, ensure your browser is up to date. MediaWiki features and some scripts are not supported by old browsers for safety reasons.

Then, purge the cache for the page to force the page to be redisplayed from its source or scripts to restart.

Those two points solve most issues.

If you have a tool like "NoScript" or ad blockers installed on your web browser, then make certain that scripts are enabled for wikipedia.org, wikimedia.org, mediawiki.org, and wikidata.org.

Test if you have problems related to user scripts or gadgets

To test if your problem is linked to user scripts or gadgets, you can try to temporarily deactivate all on-wiki scripts and stylesheets at once.

To do so, add the safemode parameter (?safemode=1) to the web address (URL) of the page on which you see the problem. Example: https://www.mediawiki.org/wiki/Help:Locating_broken_scripts?safemode=1

If the URL already includes a ?, append &safemode=1 instead. Example: https://www.mediawiki.org/w/index.php?title=Help:Locating_broken_scripts&safemode=1

If you still have problems on the page you are testing with the safe mode, and your browser is up to date, please contact a developer of MediaWiki (How to report a bug). If you don't have the problem anymore using the safe mode, it means you have an issue with a user script or gadget. You have to identify the problem.

Test if you have problems related to browser extensions

Some issues may be a result of interaction between Wikipedia and some browser extension. The easiest way to test it, is to try the same action with all extensions disabled, and the easiest way to achieve this, at least with the Google Chrome and Firefox browsers, is to repeat the operation using "anonymous browsing" or "guest mode", where the browser disables all extensions by default. If the issue disappears with anonymous browsing, try to narrow it down by temporarily disabling extensions one by one, until the "culprit" extension is found.

If you find that the problem is indeed related to a browser extension, consider reporting it to the extension developers. If you decide to report it on a discussion forum on Wikimedia wikis, please mention your browser extension in your report.

Identify the problems

The following links explain how to do this for the following browsers:

After opening them, please append ?debug=true to the web address (URL) of the page on which you see the problem. Example: https://www.mediawiki.org/wiki/Help:Locating_broken_scripts?debug=true

If the URL already includes a ?, append &debug=true instead. Example: https://www.mediawiki.org/w/index.php?title=Help:Locating_broken_scripts&debug=true

If there is a problem with JavaScript, an error should be printed in the 'console' of the developer tools.

Make sure that "JavaScript" or "JS" is enabled here, and potentially disable other output so the output does not get too noisy:

Example of results on a wiki, using Firefox debugging mode.

Click on the file name on the right. This will open the "Debugger" view. The right pane will show the code which needs to be fixed. The left pane will show which file needs to be fixed (you might need to scroll through the list to find the one file that is highlighted). Right-click on the file, to open the file that needs fixing in a new tab:

Example of results on a wiki, using Firefox debugging mode.

Due to how files are "loaded", the exact URL of the file might not always be obvious. So you may have to scroll to the top of the file to see its name.

This name may just be a comment (something like // Title).

Problems that need fixing could be in the local MediaWiki:Common.js file on that wiki, in your personal files such as User:MyUserName/common.js (or other .js files that you have under User:MyUserName/), or in the code of one of the gadgets available on that wiki, or in the code dependency definitions of the gadget defined in MediaWiki:Gadgets-definition on that wiki.

For more technical information you can check how to Toggle debug mode.

Fix the problem

You will find most of the scripts by looking in m:Special:MyPage/global.js on Meta, and locally Special:MyPage/common.js, Special:MyPage/vector.js (or similarly named pages, if you are using a different skin, such as Special:MyPage/monobook.js if you are using the MonoBook skin), and anything that is selected locally in the Special:Preferences#mw-prefsection-gadgets.

Problem on scripts can be due to multiple causes. We advise you to contact someone who knows JavaScript to help you. (If you have basic technical knowledge of JavaScript, see T164242 for hints and links to additional information.)

In the meantime, you can disable the scripts.

If the broken script is identified as a gadget, disable the gadget in your preferences.

If the broken script is on a .js page of yours, disable the script by commenting it out. Add /* at the beginning of the concerned code and */ at the end.

You can also disable the script by blanking all of the lines about it in your .js page or by commenting out by // at the start of each line concerned.

Other ways to identify broken scripts

note the gadgets and scripts you are using on your account
disable all scripts and gadgets on your account
re-enable one gadget
clear your browser cache
test if you still have problems:
- If not, go to step 3
- If yes, fix the script and go back to step 3 for other potentially broken scripts

Totally unrelated gadgets can break the strangest things. To narrow it down turn off all the gadgets in a particular section of the gadgets list in preferences, and see if that helps. Then if that doesn't work try turning off another section of gadgets. Eventually you will find the section of gadgets where the problem lies. Then turn off the gadgets in that section one by one. Before doing any of this take a screenshot of the whole gadget preferences page. This way you can get back to what you like. Firefox has a built-in screenshot tool that lets you get the whole page including the part of the page not showing on the screen.