Tor Browser is based on Firefox, and any browser add-ons or themes that are compatible with Firefox can also be installed in Tor Browser. However, disabling JavaScript will prevent many websites from displaying correctly, so Tor Browser’s default setting is to allow all websites to run scripts in "Standard" mode. Users who require a high degree of security in their web browsing should set Tor Browser’s Security Level to “Safer” (which disables JavaScript for non-HTTPS websites) or “Safest” (which does so for all websites). NoScript allows you to control the JavaScript (and other scripts) that runs on individual web pages, or block it entirely. It's accessible through "Preferences" (or "Options" on Windows) on the hamburger menu (≡), then select 'Customize' and drag the “S” icon to the top-right of the window. Tor Browser includes an add-on called NoScript. Unfortunately, JavaScript can also enable attacks on the security of the browser, which might lead to deanonymization.
JavaScript is a programming language that websites use to offer interactive elements such as video, animation, audio, and status timelines. These methods may be compatible with Tor Browser. Some video websites (such as YouTube) offer alternative video delivery methods that do not use Flash. For this reason, Flash is disabled by default in Tor Browser, and enabling it is not recommended. It can therefore reveal your real location and IP address to the website operators, or to an outside observer. Unfortunately, this software operates independently of Tor Browser and cannot easily be made to obey Tor Browser’s proxy settings. Video websites, such as Vimeo make use of the Flash Player plugin to display video content.