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.
The script is just an advanced UserInfo with more information, ability to check on other user, not just on yourself, and now, making a page for it to work is not necessary. (This function wasn't removed, though.)
The script works on Special:UserCheck. A link to the page is added in the toolbar. There, the page will ask for a name and the check begins. A button is added for ReCheck so you don't have to refresh the page to check someone else.
Another method is on the user's contributions page. A button is added after the logs named "AJAX UserCheck". An modal appears, the username is autofilled and the check begins.
(Note, while in the code.js, the script is named as CheckUser or UserCheck, the ability should not be confused with FANDOM Staff's CheckUser ability.)