The Javascript errors that the Launcher periodically displays have nothing to do with Java, or with anything the player has installed, and they have nothing to do with in-game script errors. The javascript issues are entirely on EA's end and only involve the display of the data that the Launcher provides on the startup screen (store item of the day, click here to buy TS4, etc.). These have been happening on and off for years. If you can click through the error or just close the notification box by hitting "X," it is perfectly safe to startup your game.
Needing assistance with in-game crashing and freezing, yes of course that would be a different matter.
http://nraas.wikispaces.com/Tips%20For%20Better%20Game%20Performance
