Firefox has the Sandbox and evalInSandbox(). Chrome has sandboxed execution in their content scripts (they call it isolated execution). I'm looking for the same thing in an IE browser extension. I can load a javascript file, then call evalScript(), but the code executes in the same environment as javascript that exists on the page. I need a way to run my library (which includes and is based on jQuery) in an sandboxed/isolated environment, but still allow it to modify the DOM as if it were running on the page. Jint looks promising, but cannot currently evaluate jQuery. (They can parse it.) How can I do this?