NoScript
Web Browser Addons

Only enable JavaScript, Java, and Flash for sites you trust.

Security Notes

Install NoScript and enable ‘Forbid scripts globally’ to improve the security of your browser by preventing 0day JavaScript attacks. This is a drastic option as it will render many websites unusable as they rely heavily on JavaScript.

NoScript offers a whitelist you can use to selectively enable JavaScript for sites you trust, but this is considered especially bad for your anonymity if you're using NoScript with Tor Browser.