The Lisps in which this concept has its heritage call that step "macro expansion". Granted that that won't happen properly if you use script tags to load a file

The Lisps in which this concept has its heritage call that step "macro expansion". Granted that that won't happen properly if you use script tags to load a file of Javascript with macros -- but consider, for example, the possibilities inherent in making macro expansion an integral part of the loading process carried out by a library like Require.js. Macro expansion tends to be a lot lighter-weight than compilation does, because it's a simpler transformation; there's no obvious reason why integrating it into Require, or a similar library, should be particularly difficult to accomplish.