JavaScript is designed as an open scripting language. It is not intended to replace proper security measures, and should never be used in place of proper encryption.
JavaScript has its own security model, but this is not designed to protect the Web site owner or the data passed between the browser and the server. The security model is designed to protect the user from malicious Web sites, and as a result, it enforces strict limits on what the page author is allowed to do. They may have control over their own page inside the browser, but that is where their abilities end.
