This script adds an icon to header tags, such as <h2>, <h3>, <h4>, etc. In terms of wikitext this is == Header ==. This only applies to headers in the editable content area. The icons only appear when hovering over a header to appear less obtrusive when reading a page. When these icons are clicked, the URL is altered to target that header allowing you to copy and paste the link into chat or discussions avoiding typing out potentially long headers by hand or having to navigate back to the table of contents to get a link.
This script will work on every MediaWiki skin, assuming it uses the mw-headline class and standard id for headers as found on skins that are included with default MediaWiki. This also relies on the editable content area having the id mw-content-text, again a default feature of MediaWiki.
This does not work for pages in the File namespace, due to a difference in the structure of header tags for these pages.
Note: In this example, pay close attention to the placement of commas and other punctuation. For people who aren't familiar with programming (and even those who are!), a common mistake when writing code is to accidentally delete, forget, or misplace critical symbols like commas or quotation marks. This can cause a syntax error that breaks the code. Carefully follow the convention shown here when using importArticles.