The Tor Browser enables JavaScript by default -- it would be impossible to use for most web browsing otherwise. In fact there is an argument to be made that you

The Tor Browser enables JavaScript by default -- it would be impossible to use for most web browsing otherwise. In fact there is an argument to be made that you should not disable JavaScript because it makes your fingerprint more unique to the sites you visit (you're a Tor user with JavaScript disabled). It depends on whether you value your anonymity more than the risk of potentially being attacked by bad JavaScript. Tor Browser is based on Firefox, and has a bunch of anti-fingerprinting measures built in to it which have been slowly upstreamed to Firefox (as well as ensuring the Firefox doesn't send anything without going through Tor -- something which historically has been hard to do as a Firefox user).