I know that Javascript is an incredibly unsecure way of programming a persistent game, where for instance you are doing battle calculations in an RPG and then award XP through linking to a PHP page when they win that adds XP to a database (since the player could make their own javascript to always win or just look at the PHP page that you get sent to when you win and just go there anyway).

So with that said, I'm wondering if HTML5 makes multiplayer/persistent games any safer in this regard, since I know it still uses Javascript. Or am I still doomed to rely entirely on server-side scripting for doing any calculations that award the player?