The Firefox button was removed for Firefox 29 - the "3-bar" button somewhat replaces it.

The control / pref for toggling JavaScript was removed long before the new UI was instituted, the pref is in about:config to prevent users from disabling JavaScript too easily and screwing up their Firefox unnecessarily.

javascript.enabled

The check boxes to enable/disable JavaScript and load images automatically have been removed from "Options > Content".

You can look at this extension:

• QuickJava: https://addons.mozilla.org/firefox/addon/quickjava/

• Tap the Alt key or press F10 to show the Menu Bar

In current Firefox releases (29 and later) the orange Firefox menu button has been replaced by the three-bar Firefox Menu button at the far right end of the Navigation Toolbar and this button is always visible whether the Menu Bar is visible or hidden. A consequence of this position is that you no longer can hide the Navigation Toolbar.

• There is a star like button next to the search bar on the Navigation Toolbar to bookmark the current web page and a "Show your bookmarks" button next to it to open the Bookmarks in a drop down menu.
  You can find "Show All Bookmarks" to open the Bookmarks Manager (Library) at the bottom of this drop-down list
• If you bookmark a page then "Bookmark This Page" in the Bookmarks menu changes to "Edit This Bookmark"

You can make the title bar visible via the "Title Bar" button at the bottom left in the Customize palette window. You can still have the Menu Bar visible via the right-click context menu of a toolbar to have menus like the File menu with Print (Ctrl+P) and Print Preview and the Bookmarks and History and Tools menus.

See also:

• https://support.mozilla.org/kb/learn-more-about-the-design-of-new-firefox
• https://support.mozilla.org/kb/common-questions-after-updating-to-new-firefox

JavaScript is enabled by default. To disable it, you can use the about:config preference editor. Since that is a lot of steps for a temporary change, you might prefer to use an add-on to create a toolbar button for it.

Manual Steps

(1) In a new tab, type or paste about:config in the address bar and press Enter. Click the button promising to be careful.

(2) In the search box above the list, type or paste javas and pause while the list is filtered

(3) If the javascript.enabled preference is bolded and "user set" to false, double-click it to switch it back to true.

Add-ons

Here is an example of an add-on that creates a toolbar button to flip this setting true and false when needed:

https://addons.mozilla.org/firefox/addon/quickjava/

Many of us are using Classic Theme Restorer (Customize Australis) {web link} Restore squared tabs, appmenu, add-ons bar, small button view and more on Australis UI (Windows/MacOSX/Linux + Fx 29+).

This will restore many of the things the last upgrades took away.