Select Preferences from the Firefox menu. In the pop-up window, click the Content icon. Check the Enable JavaScript check box. Close the window. To enable JavaScript in Safari (MAC): ...

Mozilla Firefox (1.5) Select 'Tools' from the top menu Choose 'Options' Choose 'Content' from the top navigation Select the checkbox next to 'Enable JavaScript' and click OK ...

Select the "Enable JavaScript" check box to allow scripts on Web pages in Firefox. Click "OK" to save the new settings and close the Options window.

Learn how to enable a visual tab switcher, much like the OS X Command-Tab application switcher, in the Firefox 3.6 beta releases.