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Help:JavaScript and CSS Cheatsheet

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Creating some custom code for your community, or for your own account? This page has more background details to help you with both.

For a more basic overview, see Help:CSS and JS customization.

Note: Community JavaScript is enabled on demand by contacting Wikia Support. Visit Help:JavaScript review process for more information.

CSS and JS cheatsheet

The tables below are summarized guides to most of CSS and JS customization pages. The most common choices are highlighted in green.

Stylesheet Located at Affected wikias Affected users Affected skins
MediaWiki:Wikia.css this wikia this wikia all users Wikia (default)
MediaWiki:Common.css this wikia this wikia all users varies
MediaWiki:Monobook.css this wikia this wikia all users Monobook
Special:MyPage/common.css this wikia this wikia you only all
Special:MyPage/wikia.css this wikia this wikia you only Wikia (default)
Special:MyPage/monobook.css this wikia this wikia you only Monobook
w:Special:MyPage/global.css Community Central all wikias you only all
Script file Located at Affected wikias Affected users Affected skins
MediaWiki:Common.js this wikia this wikia all users all
MediaWiki:Wikia.js this wikia this wikia all users Wikia (default)
MediaWiki:Monobook.js this wikia this wikia all users Monobook
Special:MyPage/common.js this wikia this wikia you only all
Special:MyPage/wikia.js this wikia this wikia you only Wikia (default)
Special:MyPage/monobook.js this wikia this wikia you only Monobook
w:Special:MyPage/global.js Community Central all wikias you only all

CSS and JS editor error checking

Wikia's CSS and JS editors have active error checking ("linting") and syntax highlighting:

  • As you type code, the page will let you know about any errors in the syntax that might have occurred.
  • Note that not every issue has to be solved - CSS (and even JS) technology is ever evolving, and browsers do not all behave identically: some messages may not require action.

Common issues

CSS issues
Issue Explanation
@import prevent parallel downloads, use <link> instead Link tags are normally used to import CSS. However, MediaWiki does not support adding your own link tags without use of JS, so this error can normally be ignored.
Expected X but found Y This means you have entered an invalid value for a property. For example, in color: foo; foo is an invalid value for the color property because it is not a color.
Use of !important !important should generally be avoided in CSS as it can makes it harder to maintain, and also makes it harder for users to override settings in their personal CSS. Most of the time, using the correct selector will help you avoid using !important.
Unknown property 'codename' Although not all CSS code is recognized by the tool (as CSS itself is a frequently updated artform), certain CSS codes can still be read when they are implemented for a certain object on the Wikia page (For example, mix-blend-mode: color-dodge;).

Advanced notes

Applying CSS to specific pages
Using CSS classes, you can apply CSS to specific pages. The <body> HTML element on Wikia articles includes a unique identifier based on the name of the page. For example, on this help page, the class is:
The general format is page-[article name], and spaces, colons, and other special characters are replaced by underscores.
There are other classes on the body tag that allow you to apply code by namespace, and more - a browser's "inspect" or "view source" functionality will let you see what is available.
Applying JS to specific pages
In mediawiki:common.js, use a switch to apply JavaScript to certain pages:
switch (mw.config.get('wgPageName')) {
    case 'page name':
        // JS here will be applied to "page name"
    case 'some other page':
        // JS here will be applied to "some other page"
Load orders
The general load order on Wikia is: core code, then local community code, then personal code.
Within each level, the load order is: "common" code, then skin-specific code.
!important in CSS
Due to CSS load orders, you may sometimes need to make use of the !important property to ensure a CSS rule is applied.
Caching issues
Every file you download from the internet gets cached. Normally that's great because it reduces traffic both for your own device and for Wikia's servers, but it can be a problem when it comes to testing design changes. It may take a while before your changes to take effect unless you use the following tricks:
Note: After saving, you may have to bypass your browser's cache to see the changes.
  • Chrome - Windows: Hold the Ctrl key and press the F5 key. OS X: Hold both the ⌘ Cmd and ⇧ Shift keys and press the R key.
  • Safari - Hold down the ⇧ Shift key and click the Reload toolbar button.
  • Firefox - Windows: Hold the Ctrl key, and press F5. OS X: Hold the ⌘ Cmd and ⇧ Shift keys, and then press R.
  • Internet Explorer - Hold the Ctrl key, and press F5 (or click the Refresh button).

You may need to manually refresh each page you recently opened to see the change there.
Popular JavaScript snippets
To get an idea of some scripts others have written that you might find useful or would like to try, take a look at the list of JS Enhancements on the Developers Wiki.
Duplicate JavaScript
Many scripts can have problems if they run multiple times on the same page. Make sure write the code such that a particular piece of code runs only once. Avoid pasting the same code in multiple files as it will likely conflict and cause confusing errors for you and other visitors.

Further reading

Further help and feedback

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