Right, that's the idea of FunctionBlob. It wraps a browser-internal representation of the optimized compiled code. The web code can instruct the browser to store that offline, without exposing its implementation-specific details to the web code. The web code can then, in a later session, retrieve that optimized code from storage as another FunctionBlob, which it can then convert into a Function. This is no different from just storing the asm.js source code in offline storage, except it avoids redoing the work of compiling and optimizing the source. (It'd still have to be stored in position-independent format and there might be some back-patching necessary when reloading it.)